What else has changed on your system ?
Does this happen after a reboot ?
Try a repair of avast. Add Remove programs, select 'avast! Anti-Virus,' click the Change/Remove button and scroll down to Repair, click next and follow.
If that doesn't work then perhaps a clean reinstall:
Download the latest version of avast
http://www.avast.com/eng/download-avast-home.html and save it to your HDD, somewhere you can find it again. Use that when you reinstall. Ensure that you scroll down and select the avast direct download link for the English version and not Cnet as that is for an on-line installation (not what you want to do). - Direct download for avast Home, English version,
http://files.avast.com/iavs4pro/setupeng.exe.
Download the avast! Uninstall Utility,
find it here and save it to your HDD.
- 1. Now uninstall (using add remove programs, if you can't do that start from the next step), reboot.
- 2. run the avast! Uninstall Utility, reboot. If step 1 failed it may be necessary to run this from safe mode, once complete reboot into normal mode.
- 3. install the latest version, reboot.
There is however, a possibility that it could be malware if after a clean reinstall this is still present.