Avast temporarily disabled when turning on computer

[Suntio]

A few weeks ago I noticed the Avast icon was temporarily disabled for a few seconds when I turned on the computer, I ran an anti-malware program which discovered and removed a trojan agent after which everything ran fine.  Recently there has been 2 occasions when Avast was temporarily disabled when I've switched on and I've run anti-malware programs but nothing has come to light.  Can anyone advise of any other reasons why Avast may be temporarily disabled?

[Chris Thomas]

In my Vista system Avast starts very late compared to my Win 7 system at the time of starting the computer.

There is a setting you can change for faster start up but it make your computer a little insecure

Go to settings>troubleshooting and check off "Load Avast! services only after loading other system services".