I've been seeing the same thing since installing the last 2 updates on my SuperAntiSpyware Free this week. The scan will hang on a file (never the same file, by the way), then errors out with a recommendation that DDA be disabled. With DDA disabled, the scan runs. However, I can re-enable DDA, scan the individual files and it works.
I've run CHKDSK on my drive and it reports no errors. I've also scanned the drive with avast! Home Edition to eliminate the possibility of a rootkit as well as uninstalled/reinstalled SAS Free.
Again, the scan hangs only started this week with the last 2 definition updates.