Load the above page, resize the window wider than the frameset, surrounding the frameset (left and right) will be extra semi random cruft.
Looks like an image problem to me, in 4.5 on side borders have a background image to them. I'll attach a test case to test this in to see if it's the body background causing problems with mozilla.
Created attachment 541 [details] this is a file with a gif image from my site as background, try it in 4.xx and in mozilla.
I tried them in build 1999062408 and the image does not show up , but does in the 4.5, actually what happenes is that the image loads, but all that is displayed is a small little dot the the left side of the screen. This definitly appears to be an image problem and not a frame problem.
Reassigning to Eric.
This was fixed. I bet it was pnunn, thanks! To verify, expand the browser window as described above. You'll now see the background image instead of 'random cruft'. Also, view the 'alternate version' above. You'll see that draws correctly now.