I have a p4 with intel 3.2 ghz processor and Win xp2 all working fine until I updated my wireless keyboard software/driver. I downloaded the update from Logitech and ran it, at the end the installer said can not find "mouclass.sys" so I searched and found it in the SP2 upgrade folder. after rebooting, the keyboard would not work. Now I can not type my password; as the only ADMINISTRATOR there is no other access to the system. when logged as another user,  the Device manager shows the keyboard with a yellow flag, but I can not update it or uninstall it because other users are not administrators. I removed the wireless keyboard and installed a standard keyboard, Windows would not recognize or acknowledge the new hardware. Both the standard and wireless keyboards work until windows is loaded (I can access the bios and press F8 to access windows in safe mode). All programs and games work fine (by other users) as long as the mouse is the only required hardware.

P.S. when I loaded Windows I had setup the Administrator with a password, then when the users were defined I setup my name with a deferent password that I change regularly.

Is there a way out of this without a total reinstall? Is there a way to enter the password (numbers only) without a keyboard?
please helpTry the following:

1. Before Windows XP loads press F8.
2. Select Last known good configuration and press Enter.I TRIED, it would not work. Windows does not seam to notice there is a hardware problem and does not recognize new hardware.1. Before Windows XP loads press F8.
2. Select safe mode and press Enter.
3. Choose the normally hidden moderator account
4. Remove all Logitech related drivers and reinstall your keyboard from the device manager.Canadian:

How are things in the Great White North? (OK, i'm showing my age with the reference to the McKenzy Bros.!)  I used to live just 20 min. or so from the Thousand Islands.

Have you tried another keyboard?  A new PS/2 keyboard will only set you back $10 (USD) and a used one will cost less than $4.  Or, if your system does not have a PS/2 port, you may purchase a USB keyboard.  

Windows XP will automatically install the USB keyboard as soon as you plug it in.

Regards,
Doc

P.S. I also think the Canadian side of Niagra Falls is a much better place to visit than the American side.  http://www.michaelstevenstech.com/XPrepairinstall.htm

^plug in a ps2 keyboard and mouse......^THANKS Raptor, it did not work. Windows refuses to start in safe mode. it kept cycling between menues without going into safe mode. but works like a charm in Normal mode. I guess it does not see the need to be in safe mode.

I have never seen in the safe mode a selection for "hidden moderator account". I tried to go into safe mode on this computer and could not see that choice.

The keyboard works fine in DOS and in Bios setup but not in windows. Any other sugestions?
SFC - System File Checker - (SFC /Scannow)

/SCANNOW
Scans all protected system files immediately.
/SCANONCE
Scans all protected system files at the next boot.
/SCANBOOT
Scans all protected system files at every boot.
/REVERT
Windows XP: Return to default settings.

Cmd mode ^Merlin_2... I can not do a repair without BACKING up my files. and I can not backup without access to my account. I am the only administrator on this machine and can not log in without the keyboard.

Is there a way to remove the logiyech drivers manually by deleting the files or editing the registry?Type edit after the command prompt...and search for the logictech drivers.....and delete them...Well I tried everything and the problem is getting bigger. I ran the repair reinstall and when it got to entering the disk "key" the setup froze and now nothing will do other than a clean install. I guess I will lose one month of data, as the last backup was end of May.

However, for those who want to learn from this....Do not have a single "administrator" on any one  machine...and backup more often.....thanks for your help. Now I will go and start a clean install.There is often an administrator in safe mode that is hidden when booting normally.Can you get to the cmd prompt......if you type help/? and bunch of commands is listed......like recover