Is this the problem?
Yep, that seems to be the problem, although I'm not ruling out other causes yet until we have a reasonable sample of poll responses.
Strongly believed to be an IE8 bug (so I'm not fixing it on the forum myself). We're patched to the latest stable version of the forum code, and I will be upgrading to the next version once I know it's been released. Allegedly this bug has a work-round included in the current beta version of the forum code, which is under test.
In the interim, anyone on IE8 who is finding the bouncing around intolerable, just click the torn page icon to the right of the address bar at the top of your IE toolbars. This forces the browser into IE7 compatability mode, which should allow you to pop your eyes back in again.