Help - Packed Generic 200 virus - can't get rid of it

I'm infected with the Packed Generic 200  virus and can't get rid of it.  It's affecting my performance and also Google - clicking on search results always takes you to adware sites.  I've read previous posts on this and have done the following:

  • run Norton Internet Security (I have the 2008 version) several times, including in safe mode
  • run Malwarebytes several times (also in safe mode with no internet connection)
  • actioned all security risks identified by the software
  • Norton identifies the virus in the following file: c:\windows\system32\gaopdxvpircap.dll

I'm stuggling to follow previous posts on this as I have Windows Vista Home Basic and previous blogs refer to XP and some of the links don't work.

All advice gratefully received