Welcome Screen Issues

 On my Optiplex280 with xp I have lost the ability change how i logon to my computer. When I boot the 

 computer up it goes to the welcome screen. I click ok and it continues to start. If i go to my user accounts and try to change a message comes up saying another program is using this file. It gives me the name

Rtlgina2,dll. I do a search and i find it in my system 32 file.The only thing i can remeber doing when this occured was trying to load a program called Print artist off of my jump drive.I deleted the program and loaded it of the disk after i had found it. Any ideas? Thanks