This has just started, sometime in the past week. I was able to complete a full scan when I last tried, six or seven days ago.
When McAfee is scanning, it suddenly stops, and I get this message: "Scanning has encountered a problem from which it cannot recover." The message specifies that the problem is "error getting scan progress." Before it stops, the scan seems to get slower, jerky even, and then it stops--always ending on a different file, but sometime before even 25% of the scanning is finished.
After I get the error message, I get a message from Windows saying that Scanning "stopped working and was closed."
I'm running Vista. Both it and McAfee's are up-to-date. There *was* a Windows Update this week....