I have had the same problems with winlogon.dll not running (on a laptop and tower with win7-32bit).
After rebooting both computers, the laptop came up in a temp profile and it worked! winlogon.dll was running. I logged out of the temp and back into my main on the laptop and is continuing to run.
Is something being written to the user profile that when you get a clean one it clears up the problem? I'm not computer saavy, so I clueless, but putting out what fixed it (I am not rebooting again for as along as I can get away with it 'cause I need the connection right now to finish a project. I'll report back here if it fails after my next reboot).