Periodically I run a boot scan overnight and have been doing this successfully in recent years. This normally ends by booting up my Windows 7 (32 bit). A few days ago when I came to look at my PC in the morning it displayed a black background and a skeleton version of Windows (not Safe Mode) but not my full installation. There were no taskbars, no desktop icons and the barest of Windows Start menu pop-up items. Using Start I can invoke Restart and then Windows 7 loads up properly and all is well again. I've tried 3 boot scans now and the result is always the same. Fortunately I can end up with a proper Windows system but its a concern and I don't know if the boot scan actually ran to completion and worked properly (it does start up correctly and starts listing the files as they are being scanned - running overnight I haven't stayed to watch it to the end). Avast 'system drive & rootkit' scan does run properly from within W7 (it reported a few files it could not scan but I'm aware of these, they are no problem and were there when the boot scan was finishing properly.
Has anyone had the same problem and can you suggest how to fix it?