Problem with 2 htacess rewrite engines

[ROTPAR]

Hi,

I got a problem what is for sure easy to solve, i just don't know how

I usw wordpress in my roots folder
vbulletin is installed in the roots forums folder....

Now... Wordpress is using a .htaccess in the root folder for the rewrite rules
... Vbulletin is also using a htaccess for rewrite rules in the roots forum folder

The problem is, the wordpress root .htaccess affects my forum in the forums folder, so if I use the htaccess for wordpress, it affects vbulletin and its own htaccess and it'S rewrite rules and makes it unusable.

I hope it's clear what I wanted to say....do you guys have any solution for that problem? THX