php 4.4.1 broke my wp install

My host recently upgraded to php 4.4.1 and since that time I can not post new entries or comments on my blog (doktorflorian.com, wp 1.5.2 running).
I get a blank page in Firefox and a a€?lost network connectiona€? (NSURLErrorDomain:-1005) from Safari.
I talked to my host on the phone and the support guy said, that it could have something to do with the mod_rewrite rules in my .htaccess. I also read somewhere that there was some kind of bug in PHP 4.4.1 as described here: https://bugs.php.net/bug.php?id=35059&edit=1. This seems to have some relevance concerning my problem.
I have no idea what this means but I’m sure someone here on the forum can help me out. What good is a blog without being able to post on it.