[PeterD]

You may just have the "frozen mouse" problem. It has nothing to do with Windows 7. IL-2 is really touchy, and if youmess something up (people are still trying to figure what it is, you mouse will freeze at the main menu. The only way around this is:
1. Reinstall from scratch
2. press your "windows" button (to the left of Alt) and then double click the IL-2 program in the task bar.

Me, I opt for a reinstall to avoid the constant mouse freeze.

Reinstalling the game won't fix anything. All you need to do is once you click on the game icon, don't do anything until the game is loaded. If the mouse "freezes", CTRL+ESC to jump to desktop, then click on IL2 in the taskbar to give it focus again, then hit the CONTROL key once (or same procedure with the Windows key, no control key required). The game freezes when it loses focus before it has finished loading, it happens in all versions, modded or not.