I have been running Avast! 4.8 Home Edition on 2 Vista PCs for a week with no problems. Today, when opening Outlook 2007 with a POP3 email account, I get the error:
avast!: Cannot scan the message body
Error code is 80004004
Unspecified error in AAVM module.
AavmCheckFile failed
In the task bar it says avast! MS Outlook/Exchange provider is working until I click Ok on the error dialog.
Any suggestions, please?
First ensure that you have the latest version 4.8.1290, if not do a manual program update.
I’m using 4.8.1229.
Time to update then 
As DavidR said, 4.8.1290 is the latest version.
Try to update the program, and if the problem still exist after the update, come back here
That sorted it, thanks very much.
No problem, glad I could help.
Always best to start with the latest version before chasing any fault as it could be time wasted, certainly in this case ;D
Welcome to the forums.
Thanks for the welcome and your help. On the question of program updates, does Avast! not update automatically from time to time?
The VPS updates happen automatically, the program updates because they are going to be much larger check and Ask if you want to update now (avoids kicking off a large update whilst you are busy). Program Settings > Update (Basic) shows the default settings.
The program updates ate cycled over a 7 day period to balance server load, so this on is very recent (19/11/2008), so you may not have been lucky to have been notified early in this 7 day cycle.