Can you do a System Restore to a time before the message popped up ?
You can also run System Restore from a Command Prompt if you are unable to boot to Windows.
Press F8 just after BIOS post messages and choose Command Prompt. Type in
C:\Windows\System32\rstrui.exe
If your Windows is installed on some other drive than C:, change C: to it.
Please note I have never used F8 method at all with Win 7 and I do not know what menu options will appear there. I assume the menu will be the same with earlier Windows versions.
Or if you have a Win 7 disk, repair your Win 7 installation.