It refers to svchost.exe which is responsible for starting and maintaining loads of Windows services.
Recent occurrence? Done disk checks, virus scans, antispyware scans? Try Vista system file check; click here
Look in event viewer for red or yellow warnings matching the time(s) you experience problems.Type
eventvwr.msc in the start menu search box and press return.
Expand Windows Logs and take a look through the Application and System logs