Malicious URL Blocked Message keeps popping up. Please help!!

Avast keeps flashing this red message. I did a scan on my computer and nothing. What does this mean?? How do I get rid of it??

Mike

Infection Details
URL: http://includeit.info/include.js?id
Process: C:\Program Files (x86)\Mozilla Firefox\f…
Infection: URL:Mal

This needs further analysis by a malware removal specialist:
Go to this topic http://forum.avast.com/index.php?topic=53253.0 for information on Logs to assist in cleaning malware.
Use the information about getting and using the tools and attach the logs here, not in the LOGS topic.