I have the exact same problem, but so far my registry investigations have turned up nothing, for some reason it keeps resetting them. The relevant key seems to be:
While I couldn't tell you exactly what each bit does, if you google StuckRects2 there is some info floating around, none of it RE: win 7 unfortunately.
I have been trying to change the value to what my working windows 7 install has, which is:
28 00 00 00 FF FF FF FF
02 00 00 00 00 00 00 00
4A 00 00 00 30 00 00 00
00 00 00 00 00 00 00 00
4A 00 00 00 1A 04 00 00
However it keeps changing it back to its normal value when I reboot/logoff, so i'll keep trying and keep ya posted if i get it fixed.
I am curious as to what caused it, I just upgraded from vista and i suspect it may have been MultiMon or ObjectDock which caused the problems, were you running either of these before you upgraded?