.....STOP : 0x000000D1 ( 0x00000000,0x00000002,0x0.......
Driver_IRQL_NOT_LESS_OR_EQUAL_
This error usually is caused by outdated CD Creator drivers or similar CD writing/reading software. I have not seen this error with Avast
New is the network sheild in 4.5 can this cause the problems with my firewall ?
NO. The new Avast Network Shield asks more like an intrusion detection filter than a true firewall. There is no known conflict with Kerio.
As for obtaining an earlier version, the subject has been discussed here in the Forum, and the general consensus is that we move forward, not backward. If an "error" arises, then we work on fixing it.
At this point, I would update all drivers and Windows OS.
Uninstall Avast using the Removal utility but DO NOT install it until you see if the system works normally.
This way we can pinpoint the cause and assist you in a better manner.
Good luck.