The main forum page (and the pages under that) is now much wider than it was just a few hours ago. I have to scroll to the right to see the things on the right-hand margin (like the User CP with my avatar, the X Marks Sponsors banner, etc.). Normally, that doesn't occur unless someone posts an extra-large pic to a thread, and it only happens on that thread. Even going to 75% zoom - which makes the text really tiny - didn't fully overcome the change in size.

I have cleared my cache, temp files, etc.

If it helps, I'm running IE 8.0, Windows XP, SP3. I have a 15" LCD monitor. My screen resolution is set at 1024 x 768. Other websites do not appear to have changed, so it doesn't appear to be something on my PC (a virus, updates to Windows or IE, etc.).

I don't have any other browsers installed, so I don't know if this occurs in other browsers.