lot of "Invalid URI in request GET" suddenly

[krisen]

Using:

FreeBSD 6.1-RELEASE
Apache 2.2.3
PHP 5.1.4 (with eAccelerator v0.9.5-rc1)

Site is working fine when suddenly /var/log/httpd-error.log is "filled" with "Invalid URI in request GET ..."

The outout in httpd-error.log goes on until I restart apache. The site is "working", though I get more than 50% of page loads as "Bad Request. Your browser sent a request that this server could not understand."

I'm using mod_rewrite and virtual hosts if it might have anything to do with it...

Inside of the <Directory> tag i have this (chrizz.nu is only a development server):

RewriteEngine on

RewriteCond %{HTTP_HOST} !^www\.chrizz\.nu/?$ [NC]
RewriteRule ^(.*)$ http://www.chrizz.nu/$1 [R=301,L]
RewriteCond %{REQUEST_URI} !^/forum/?$ [NC]
RewriteCond %{REQUEST_URI} !^/events/?$ [NC]
RewriteCond %{REQUEST_URI} !^/annonser/?$ [NC]
RewriteCond %{REQUEST_URI} !^/mypage/?$ [NC]
RewriteCond %{REQUEST_URI} !^/links/?$ [NC]
RewriteCond %{REQUEST_URI} !^/faq/?$ [NC]
RewriteCond %{REQUEST_URI} !^/temp/?$ [NC]
RewriteCond %{REQUEST_URI} !^/gallery/?$ [NC]
RewriteCond %{REQUEST_URI} !^/phpadsnew/?$ [NC]
RewriteCond %{REQUEST_URI} !^/[0-9]+$ [NC]
RewriteRule ^([^/\.]+)/?$ /mypage/index.php?user=$1 [L]

I appreciate any suggestions.

Thanks.