A long ago we shared a solution for "Windows 7 Lock-up While Using Windows Photo Viewer" which involved dllhost.exe's incompatibility with Kaspersky Antivirus. I recently faced a similar issue where Microsoft's genuine dllhost.exe file was constantly using 25% of CPU with ever increasing RAM (a memory leak) consumption, this time it was not the Kaspersky incompatibility causing the issue but a Windows 7 bug how it handles thumbnail generation. The reason for the issue was a broken video download on my Desktop, Windows was trying to generate thumbnail for that broken/incompatible video file and failing causing the constant CPU usage - the solution was to simply delete the problematic file or move it to a inner folder in which case the problem will occur only when accessing that particular folder.

Since past few days my Windows 7 PC started freezing while using "Windows Photo Viewer" locking up the entire system, I was able to move my mouse and the audio-player continued playing music but Ctrl-Alt-Delete, launch of any application, or shutdown/restart the computer did not worked. The system just froze and the only solution was to do a restart/shutdown using physical power buttons, thankfully we can get rid of this bug using two methods as demonstrated ahead.