Greetings , I have a Dell Deminsions 3100 pc this pc uses only usb keyboard and mouse there are no ps2 ports on the pc.My problem started after I moved from Montana and left the dell usb keyboard in storage in Montana .when I set the pc back up I did have a ps2 keyboard so I hooked it up to the pc via a usb to ps2 adapter.the mouse is a wireless optical mouse.when I turned the pc on it starts up shows the Dell logo the lights on the keyboard and mouse come on but when windows xp boots up I get to the user log on screen but the keyboard and mouse do not work so I can not log on. But if I go into the bios od anything before windows boot up the keyboard and mouse work fine .so the problem must be something with windows xp.I even went back to the Dell defalt settings but no change.I have searched the internet and found that others have had the same problem but have not found out how to solve the problem.I can not do a restore in windows because I cannot log on and this model Dell pc does not come with restore discs .this pc was bought new from Dell about a year and a half ago .I sure hope someone here can help because I am at a lost.Thanks ...Bob