Have you rebooted ?
If not do so, if that doesn't resolve it - Try a repair of avast:
XP - Add Remove programs, select 'avast! Anti-Virus,' click the Change/Remove button and scroll down to Repair, click next and follow.
Vista, win7 - Control Panel, Programs & Features, uninstall a program, select 'avast! Anti-Virus,' click the Change/Remove button and scroll down to Repair, click next and follow.
You may need to reboot after the repair.
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Note: this should have been in its own new topic as it isn't directly related to the subject of this topic.
If after the above you still have problems:
- Please start a New Topic of your own here
http://forum.avast.com/index.php?board=2.0 (click the New topic button at the top of the page see image) as this is unrelated to the original subject and will just confuse the topic and we will try to help.