We will need more information to be able to help you:
- Is this anything related to avast?
- Which OS are you using? Is it up to date?
- What avast! version?
- Which actions have you taken to try solving the problem?
- Any other security programs that could interfere?
- Any useful information into Control Panel > Administrative Tools > Events, specially ‘Errors’.
To know how to post a screenshot, see http://forum.avast.com/index.php?topic=8982.0
You can use Gadwin PrintScreen to get a screenshot (http://www.gadwin.com/printscreen/) or the free version of WinSnap 1.1.10 (http://www.filehippo.com/download_winsnap/?2173).
If you’re using Windows XP SP2, please, check also http://forum.avast.com/index.php?topic=28579