Forum Internal Server Error with vb4?
 

We have installed vb4 in a seperate hidden folder* where we are currently developing it before upgrading the actual live forums.

However* ever since installing it I started often getting "Internal Server Error" (500) whenever I am saving a style template.
It doesn't happen to all the templates* only some specific ones (for instance vbulletin.css gives that error).

The original 3.8.4 works fine though.

Any ideas why this would be happening?