Failure of power option isnt likely to be a virus problem... Either some setting problem or maybe some file is corrupted... Run a sfc /scannow on your system to verify system files are okay... Also, are you logging in with admin priviledges?
Alternatively, you can make use of powercfg.exe as given in *support.microsoft.com/kb/324347 to create a batch file and execute it at every startup (possibly as a service)...
Arun