htaccess or something else

Hi,

All of a sudden my site has stopped - just a blank page frontend/backend.

I contacted my host - Lunarpages and they have told me it's a .htaccess problem ??

Well, the htaccess that's on the site has been there for months and it has only just stopped the site - of course Lunar havent changed anything .... <peh>

Here's a look at my htaccess - can some one have a look and suggest something please?

-----------------------------------

AddHandler application/x-httpd-php5 .php5 .php4 .php .php3 .php2 .phtml
AddType application/x-httpd-php5 .php5 .php4 .php .php3 .php2 .phtml
# Comment the following line (add '#' at the beginning)
# to disable mod_rewrite functions.
# Please note: you still need to disable the hack in
# the vBSEO control panel to stop url rewrites.
RewriteEngine On

# Some servers require the Rewritebase directive to be
# enabled (remove '#' at the beginning to activate)
# Please note: when enabled, you must include the path
# to your root vB folder (i.e. RewriteBase /forums/)
#RewriteBase /

#RewriteCond %{HTTP_HOST} !^www\.yourdomain\.com
#RewriteRule (.*) http://www.yourdomain.com/forums/$1 [L,R=301]

RewriteRule ^((urllist|sitemap_).*\.(xml|txt)(\.gz)?)$ vbseo_sitemap/vbseo_getsitemap.php?sitemap=$1 [L]

RewriteCond %{QUERY_STRING} !vbseourl=
RewriteCond %{REQUEST_URI} !(admincp/|modcp/|chat|cron)
RewriteRule ^(.*\.php(/.*)?)$ vbseo.php?vbseourl=$1 [L,QSA]

RewriteCond %{REQUEST_FILENAME} !\.(jpg|gif)$
RewriteRule ^(archive/.*)$ vbseo.php?vbseourl=$1 [L,QSA]

RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !^(admincp|modcp|clientscript|cpstyles|images)/
RewriteRule ^(.+)$ vbseo.php?vbseourl=$1 [L,QSA]

# start .htaccess file - change /YOUR-PHOTOPLOG_DIR/ to your photoplog directory
RewriteRule /photoplog/file_([0-9]+)\.jpg$ /photoplog/file.php?n=$1 [L]
# end .htaccess file

I would try to remove directives from .htaccess one-by-one to see if that helps, to determine which one causes the issue (if it's related to .htaccess at all).