raman
2
You can start your PC in safe mode and let Avast scan your PC again. Than it should be able to delete the file.
You also try Avast and Spybotsd (use Google or Boardsearch) for a downloadlink. Download/install/update them and scan your PC.
If there are still some problems left, post a hijackthis log: www.hjt.klaffke.de/en