Error log, who can explain?

Sometimes when i change or create a page i get a page with the following message “Error establishing a database connection”.
When i refresh the page , it’s all back to normal.
But… I got a error_log with lots of text, here’s a little piece of it:

[09-Jun-2011 09:53:21] PHP Fatal error:  Call to undefined function  wp_cache_get() in /home/werdt/public_html/wp-includes/functions.php on line 336
[09-Jun-2011 09:53:21] PHP Fatal error:  Call to undefined function  wp_cache_get() in /home/werdt/public_html/wp-includes/functions.php on line 336
[09-Jun-2011 09:53:21] PHP Fatal error:  Call to undefined function  wp_cache_get() in /home/werdt/public_html/wp-includes/functions.php on line 336
[09-Jun-2011 09:53:21] PHP Fatal error:  Call to undefined function  wp_cache_get() in /home/werdt/public_html/wp-includes/functions.php on line 336
[09-Jun-2011 09:53:21] PHP Fatal error:  Call to undefined function  wp_cache_get() in /home/werdt/public_html/wp-includes/functions.php on line 336
[09-Jun-2011 09:53:22] PHP Fatal error:  Call to undefined function  wp_cache_get() in /home/werdt/public_html/wp-includes/functions.php on line 336
[09-Jun-2011 09:53:22] PHP Fatal error:  Call to undefined function  wp_cache_get() in /home/werdt/public_html/wp-includes/functions.php on line 336
[09-Jun-2011 09:53:22] PHP Fatal error:  Call to undefined function  wp_cache_get() in /home/werdt/public_html/wp-includes/functions.php on line 336
[09-Jun-2011 09:53:22] PHP Fatal error:  Call to undefined function  wp_cache_get() in /home/werdt/public_html/wp-includes/functions.php on line 336
[09-Jun-2011 09:53:22] PHP Fatal error:  Call to undefined function  wp_cache_get() in /home/werdt/public_html/wp-includes/functions.php on line 336
[09-Jun-2011 09:53:23] PHP Fatal error:  Call to undefined function  wp_cache_get() in /home/werdt/public_html/wp-includes/functions.php on line 336
[09-Jun-2011 09:53:23] PHP Fatal error:  Call to undefined function  wp_cache_get() in /home/werdt/public_html/wp-includes/functions.php on line 336
[09-Jun-2011 09:53:23] PHP Fatal error:  Call to undefined function  wp_cache_get() in /home/werdt/public_html/wp-includes/functions.php on line 336
[09-Jun-2011 09:53:23] PHP Fatal error:  Call to undefined function  wp_cache_get() in /home/werdt/public_html/wp-includes/functions.php on line 336
[09-Jun-2011 09:53:24] PHP Fatal error:  Call to undefined function  wp_cache_get() in /home/werdt/public_html/wp-includes/functions.php on line 336
[09-Jun-2011 09:53:24] PHP Fatal error:  Call to undefined function  wp_cache_get() in /home/werdt/public_html/wp-includes/functions.php on line 336
[09-Jun-2011 09:53:24] PHP Fatal error:  Call to undefined function  wp_cache_get() in /home/werdt/public_html/wp-includes/functions.php on line 336
[09-Jun-2011 09:53:24] PHP Fatal error:  Call to undefined function  wp_cache_get() in /home/werdt/public_html/wp-includes/functions.php on line 336
[09-Jun-2011 09:53:24] PHP Fatal error:  Call to undefined function  wp_cache_get() in /home/werdt/public_html/wp-includes/functions.php on line 336
[09-Jun-2011 09:53:27] WordPress database error MySQL server has gone away for query INSERT INTO <code>vg66_options</code> (<code>option_name</code>, <code>option_value</code>, <code>autoload</code>) VALUES ('rewrite_rules', 'a:16980:{s:47:\&quot;category/(.+?)/feed/(feed|rdf|rss|rss2|atom)/?$\&quot;;s:52:\&quot;index.php?category_name=$matches[1]&feed=$matches[2]\&quot;;s:42:\&quot;category/(.+?)/(feed|rdf|rss|rss2|atom)/?$\&quot;;s:52:\&quot;index.php?category_name=$matches[1]&feed=$matches[2]\&quot;;s:35:\&quot;category/(.+?)/page/?([0-9]{1,})/?$\&quot;;s:53:\&quot;index.php?category_name=$matches[1]&paged=$matches[2]\&quot;;s:17:\&quot;category/(.+?)/?$\&quot;;s:35:\&quot;index.php?category_name=$matches[1]\&quot;;s:44:\&quot;tag/([^/]+)/feed/(feed|rdf|rss|rss2|atom)/?$\&quot;;s:42:\&quot;index.php?tag=$matches[1]&feed=$matches[2]\&quot;;s:39:\&quot;tag/([^/]+)/(feed|rdf|rss|rss2|atom)/?$\&quot;;s:42:\&quot;index.php?tag=$matches[1]&feed=$matches[2]\&quot;;s:32:\&quot;tag/([^/]+)/page/?([0-9]{1,})/?$\&quot;;s:43:\&quot;index.php?tag=$matches[1]&paged=$matches[2]\&quot;;s:14:\&quot;tag/([^/]+)/?$\&quot;;s:25:\&quot;index.php?tag=$matches[1]\&quot;;s:45:\&quot;type/([^/]+)/feed/(feed|rdf|rss|rss2|atom)/?$\&quot;;s:50:\&quot;index.php?post_format=$matches[1]&feed=$matches[2]\&quot;;s:40:\&quot;type/([^/]+)/(feed|rdf|rss|rss2|atom)/?$\&quot;;s:50:\&quot;index.php?post_format=$matches[1]&feed=$matches[2]\&quot;;s:33:\&quot;type/([^/]+)/page/?([0-9]{1,})/?$\&quot;;s:51:\&quot;index.php?post_format=$matches[1]&paged=$matches[2]\&quot;;s:15:\&quot;type/([^/]+)/?$\&quot;;s:33:\&quot;index.php?post_format=$matches[1]\&quot;;s:12:\&quot;robots\\.txt$\&quot;;s:18:\&quot;index.php?robots=1\&quot;;s:14:\&quot;.*wp-atom.php$\&quot;;s:19:\&quot;index.php?feed=atom\&quot;;s:13:\&quot;.*wp-rdf.php$\&quot;;s:18:\&quot;index.php?feed=rdf\&quot;;s:13:\&quot;.*wp-rss.php$\&quot;;s:18:\&quot;index.php?feed=rss\&quot;;s:14:\&quot;.*wp-rss2.php$\&quot;;s:19:\&quot;index.php?feed=rss2\&quot;;s:14:\&quot;.*wp-feed.php$\&quot;;s:19:\&quot;index.php?feed=feed\&quot;;s:22:\&quot;.*wp-commentsrss2.php$\&quot;;s:34:\&quot;index.php?feed=rss2&withcomments=1\&quot;;s:47:\&quot;test/continent-antarctica/attachment/([^/]+)/?$\&quot;;s:32:\&quot;index.php?attachment=$matches[1]\&quot;;s:57:\&quot;test/continent-antarctica/attachment/([^/]+)/trackback/?$\&quot;;s:37:\&quot;index.php?attachment=$matches[1]&tb=1\&quot;;s:77:\&quot;test/continent-antarctica/attachment/([^/]+)/feed/(feed|rdf|rss|rss2|atom)/?$\&quot;;s:49:\&quot;index.php?attachment=$matches[1]&feed=$matches[2]\&quot;;s:72:\&quot;test/continent-antarctica/attachment/([^/]+)/(feed|rdf|rss|rss2|atom)/?$\&quot;;s:49:\&quot;index.php?attachment=$matches[1]&feed=$matches[2]\&quot;;s:72:\&quot;test/continent-antarctica/attachment/([^/]+)/comment-page-([0-9]{1,})/?$\&quot;;s:50:\&quot;index.php?attachment=$matches[1]&cpage=$matches[2]\&quot;;s:40:\&quot;(test/continent-antarctica)/trackback/?$\&quot;;s:37:\&quot;index.php?attachment=$matches[1]&tb=1\&quot;;s:60:\&quot;(test/continent-antarctica)/feed/(feed|rdf|rss|rss2|atom)/?$\&quot;;s:49:\&quot;index.php?attachment=$matches[1]&feed=$matches[2]\&quot;;s:55:\&quot;(test/continent-antarctica)/(feed|rdf|rss|rss2|atom)/?$\&quot;;s:49:\&quot;index.php?attachment=$matches[1]&feed=$matches[2]\&quot;;s:48:\&quot;(test/continent-antarctica)/page/?([0-9]{1,})/?$\&quot;;s:50:\&quot;index.php?attachment=$matches[1]&paged=$matches[2]\&quot;;s:55:\&quot;(test/continent-antarctica)/comment-page-([0-9]{1,})/?$\&quot;;s:50:\&quot;index.php?attachment=$matches[1]&cpage=$matches[2]\&quot;;s:40:\&quot;(test/continent-antarctica)(/[0-9]+)?/?$\&quot;;s:49:\&quot;index.php?attachment=$matches[1]&page=$matches[2]\&quot;;s:50:\&quot;test/continent-noord-amerika/attachment/([^/]+)/?$\&quot;;s:32:\&quot;index.php?attachment=$matches[1]\&quot;;s:60:\&quot;test/continent-noord-amerika/attachment/([^/]+)/trackback/?$\&quot;;s:37:\&quot;index.php?attachment=$matches[1]&tb=1\&quot;;s:80:\&quot;test/continent-noord-amerika/attachment/([^/]+)/feed/(feed|rdf|rss|rss2|atom)/?$\&quot;;s:49:\&quot;index.php?attachment=$matches[1]&feed=$matches[2]\&quot;;s:75:\&quot;test/continent-noord-amerika/attachment/([^/]+)/(feed|rdf|rss|rss2|atom)/?$\&quot;;s:49:\&quot;index.php?attachment=$matches[1]&feed=$matches[2]\&quot;;s:75:\&quot;test/continent-noord-amerika/attachment/([^/]+)/comment-page-([0-9]{1,})/?$\&quot;;s:50:\&quot;index.php?attachment=$matches[1]&cpage=$matches[2]\&quot;;s:43:\&quot;(test/continent-noord-amerika)/trackback/?$\&quot;;s:37:\&quot;index.php?attachment=$matches[1]&tb=1\&quot;;s:63:\&quot;(test/continent-noord-amerika)/feed/(feed|rdf|rss|rss2|atom)/?$\&quot;;s:49:\&quot;index.php?attachment=$matches[1]&feed=$matches[2]\&quot;;s:58:\&quot;(test/continent-noord-amerika)/(feed|rdf|rss|rss2|atom)/?$\&quot;;s:49:\&quot;index.php?attachment=$matches[1]&feed=$matches[2]\&quot;;s:51:\&quot;(test/continent-noord-amerika)/page/?([0-9]{1,})/?$\&quot;;s:50:\&quot;index.php?attachment=$matches[1]&paged=$matches[2]\&quot;;s:58:\&quot;(test/continent-noord-amerika)/comment-page-([0-9]{1,})/?$\&quot;;s:50:\&quot;index.php?attachment=$matches[1]&cpage=$matches[2]\&quot;;s:43:\&quot;(test/continent-noord-amerika)(/[0-9]+)?/?$\&quot;;s:49:\&quot;index.php?attachment=$matches[1]&page=$matches[2]\&quot;;s:69:\&quot;continenten/zuid-amerika/continent-europa-klein/attachment/([^/]+)/?$\&quot;;s:32:\&quot;index.php?attachment=$matches[1]\&quot;;s:79:\&quot;continenten/zuid-amerika/continent-europa-klein/attachment/([^/]+)/trackback/?$\&quot;;s:37:\&quot;index.php?attachment=$matches[1]&tb=1\&quot;;s:99:\&quot;continenten/zuid-amerika/continent-europa-klein/attachment/([^/]+)/feed/(feed|rdf|rss|rss2|atom)/?$\&quot;;s:49:\&quot;index.php?attachment=$matches[1]&feed=$matches[2]\

Does anybody know what the problem is?
If i watch in functions.php on line 336, there is the following text:
$notoptions = wp_cache_get( 'notoptions', 'options' );

I have a minimum of plugins:
Exclude pages, w3 total cache, xml sitemaps, revision control, all in one seo pack

And i use permalink structure
/%postname%