I reported elsewhere that v4 (4.0.424 and the previous version) hung when doing an On-Demand scan at 69%. Tonite I tried installing from scratch the new v4.0.437. Same result with a little twist. This time when it hung at 69%, I tried opening a log file and scrolling it. When I closed the log files and went back to the scan, it had resumed. However, it stalled again at 84%. Again, going to the log fukes and back again got the scan going again. It finally stalled out again completely at 98%. At that point, I could not get to the log files to hope for a resume. This time I was dead in the water. After a reboot (holding down the power button on this laptop), I was able to look at a log file again and the last entry indicated running out of free memory or a problem with temp files. As another test, I manually tested each folder in C:\ and the process was fine. It's only the full on-demand scan that seems to be broken, at least on my Vista Home Premium SP2 laptop. While I've got you, what is the difference between "Scan" and "Scan as Administrator"?