@ copgtp,
When you ran MBAM or Avast scans and you found something (infection/virus), did you quarantine it or put it in the Virus Chest or do anything else with it?
If you still got the pop-up on installation, even though things appear to be working, my concern is that you still have something (malware) hidden inside your machine.
- Had you uninstalled the previous AV's prior to installing Avast?
- Did you run Dr.WebCureIt, and what were the results? How about OTL?
- Did you update your software? Here is an easy way to update your software with the free Senunia Software Inspector:
http://secunia.com/vulnerability_scanning/personal/ - it will give you the vendor's direct download link making it easy to install patches if needed. Many of us scan our machines weekly since software changes so often.
- Does your machine appear to be running/acting normally?