computer crashes and lagging internet

Hi.
I purchased Avast Pro for two years on the sixth of this January after the new year. My problem is that since that time I have had 4 blue screen crashes. Opening web pages lag for what seems ages, and I cannot shut down the computer without having to press the button. The computer has been checked for viruses and its checked none. Mid January I unistalled the program and reinstalled it but have had no improvement so far.

  • Which version of Avast Pro…?
  • OS…? (32/64 Bit…? - which SP/Build…?)
  • Other security related software installed…?
  • Which AV(s) did you use before Avast…?

Here’s the detail

Avast Pro Antivirus
version: 11.1.2245
OS : Windows 7 64bit
which SP: Service Pack 1
other AV : Spybot and Zone Alarm.

Last year a tech guy installed Avast.

Remove Spybot.
The teatimer is not compatible with avast.
Besides that, it used to be a good tool but for several years it has a huge lack of detection.

Also remove Zone Alarm, it is not just a firewall anymore for years.
It also installs (parts of) their av and they can interfere with avast.