PC won't start after installing Avast 7

Installed on laptop with no problem but on house PC …oh dear. Installed yesterday and went to bed leaving a full scan in progress. Came down this morning and was prompted to re-start which I did. But it won’t re-start and tells me there is a problem with Windows and I should try the original set-up disc (XP)R.and press I have tried that but nothing changes. Anyone got any suggestions? I’m useless at this …

thanks.

  • Which avast!..?? (Free/Pro/IS)
  • Which version…??
  • OS…?? (32/64 Bit…? - which SP…?)
  • Other security related software installed…??
  • Which AV did you use before avast!..??

@jonggang

can you start in safe mode ?

what antivirus did you have before avast?
did you uninstall it before installing avast?