I have earlier updated Avast Internet Security to the latest version and on the required reboot got the BSOD within a few minutes.
Initially I did not associate it with the update. I got the usually serious system error message and the laptop (XP) went into disc checking finding no problems. This kept on repeating with no more than a few minutes between intervals of BSOD. I realised that this was occurring almost straight away when I tried to get on to the internet (failed to do so each time).
I then did a restore to a few days ago and the problem has gone. The only changes to the laptop have been the update to the Avast I. S.
Is there a known problem with the latest update and Windows XP?
Run uninstaller from above. You will be directed to reboot into safe mode, do so.
Reboot.
Install from above. note: If possible clean-up any leftovers using CCleaner before re-installing avast.
Reboot and register.