It started last night. My Avira Antivirus detected a virus on winmm.dll so I guess it deleted it but the system was still working fine until I restarted it today and a lot of error message from my installed programs popped up. I restarted it several times and tried system restore point and the error messages were gone. But now I am asked to activate my Windows OS or else it will expire in the next 5 days. But when I am trying to activate it using the activate button on the Windows Activation control panel I receive error 0x8007007b message. I tried using the Command Prompt method and it said that the product is successfully activated but the activation message on the control panel would still be there. What should I do? I'm thinking about reinstalling the OS but is there any other way to fix this? Please help