which software do you use & which Windows......?
as per my knowledge this is Some Windows File which is located in C:\Windows\system32
May be the file is corrupt
try running "scannow /sfc" (i.e. system file checker)
or just giveme ur email id i'll mail U the new "vssvc.exe" file replace it with the original from
C:\Windows\system32
1st try SFC.......... than tell wht happen