First post here, but I thought I would spread the love and provide a tip.
Basically, what happened for me was that IntelliJ IDEA would start minimized. License, configuration, startup dialogs would show, the window outline would quickly flash and then minimize and no matter what I did, the IDE would not maximize again. If I chose to close it from the taskbar, the "Do you wish to exit" dialogue would appear.
After re-installs (both IDEA and Java SDK), relocations of install directories and restarts, I was about ready to throw in the towel and rollback to Vista ('cause my excuses to work were wearing thin )
Anyway, as an option I should've tried early on, I went and turned off Aero and I could maximize IntelliJ again (must have forced Windows to redraw it). Switching Aero back on and it still maximizes.
So, thought I would post it here if anybody using Windows 7 RC1 has the same problem they have a solution to search from.