restoring welcome screen/fast user switching

I have 3 User Accounts on my Windows XP system at home. Due to some reason last month I disabled default welcome screen and fast user switching. I did this by un-checking their check box in the User Account settings. Now as I need them back again, system is not allowing me to do so. Every time I try tuning them On, I use to get the following error message:

"A recently installed program has disabled the welcome screen and fast user switching. To restore....you must uninstall....the following file may help....vrlogon.dll."

I don’t know which program is it talking about, also my System Restore was turned off since start hence there is no restore point. What can I do now? Please help.

I would like to know whether the system is any Desktop Or a Laptop because the file mentioned in the error message vrlogon.dll seems to be related to an integrated FingerPrint Reader. And it use to be on Laptops itself. So if you are using any laptop, probably Lenovo Thinkpad, then just check the following article and see if it helps you in any way:

Fingerprint Reader protected logon causes vrlogon.dll error - ThinkPad T42, T42p, Z60m, Z60t