help please: blog import error

I’ve been trying to import blog posts from one WordPress site to another and have had zero luck. I’ve tried upping the upload size in the user.ini, uploading it as a .gz file, nothing works. I get to the part where I need to select the author name and then I get this error:

Fatal error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 2789 bytes) in /home/indianajane/public_html/wp-content/plugins/wordpress-importer/parsers.php on line 589

On line 589 is:
preg_match_all( '|<wp:comment>(.+?)</wp:comment>|is', $post, $comments );

There are a lot of spam comments on the exported blog posts (that I’m trying to import onto the new site) but I’m not sure if that has to do with the error and if so, how to remove them?

The sites are both hosted through GoDaddy and they were of no help.