This solution worked for the guy who suggested it and it worked for me. Having the exact same problem described here with error code 41 and working keyboard (usb and ps2) up until windows loads drivers. I didn't even delete the Upper Filters entry, just the mention of lxsassc.exe.
http://forums.techguy.org/hardware/447524-keyboard-error-code-41-a-2.html
Very last posting listed as solved.
(Quoted Text)
"I solved my problem by removing an item from the UpperFilters for the keyboard in the registry. It's under:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\4D36E96B-E325-11CE-BFC1-08002BE10318
There was an entry for keykey which was leftover from spyware removal action."
