My Windows 7 installation is screwed up. Something's fundamentally wrong, but I don't know what. Taskbar icons reverted to a default icon, like they couldn't be found, shortcuts all stopped working, saying it couldn't find the file, the background during the login screen reverted to some default flowery background instead of the HP background it usually has, I navigated into the Windows\System32 folder and double-clicked on applications, and it still said it couldn't find them.
I recently installed software meant for older versions of Windows, which may be at fault. I tried to uninstall it but it wouldn't work, then offered to remove the listing from Add/Remove programs.
I did a disk check and memory check and there are no problems.
I did a few System Restores this morning, and it couldn't complete correctly ("unspecified error 0x80070067"), but afterward, shortcuts now work again, but the taskbar icons are still wrong, and applications seem to be having trouble finding their configuration files.
Best Answer
It looks like you've somehow unset the %SystemRoot% environment variable.
This should be set to C:\Windows (if your main drive is C:)
This can be done at an elevated command prompt using
set SystemRoot=C:\Windows