avast update making my windows unstable

Hi,
I have windows 7 64 bit. The subscription is active. Last month Avast reported that it wants to update device drivers. I did that. After that the system went unstable. Wouldnt boot. Even if it boots, it wouldn’t respond after 10-15 mins (hard reset was the only option). I did a system restore to a point just before Avast update. The system was back to normal. Today Avast reported Firewall is off and needs update. I did that and ended up with system hangup issue. Right now I again restored back to a good point. System looks good. But firewall is turned off. What should I do ? If I upgrade system will hang, if I don’t then firewall can not be turned on ?

Any help appreciated.

Thanks
Naveen