Main Table Width problem with IE + FF

[CP,]

We have made some changes to our forum and our forums Main Table Width is not a % but rather set to a specific measurement in pixels.

Here is the problem. The forum is showing up perfectly fine with IE but whereas when viewing it in FF the Main Table Width dosent change at all. It is showing as being fully expanded as if i had set it to 100% to adjust to the browser size. But that is not the case as it is set in pixels.

I was viewing the vb.org forum and it seems to be fine in both IE and FF, so i really cannot see where i was going wrong, all i had done was change the Main Table Width from a % to a specific pixel.

So i was wondering if i was missing anything?

Cheers!