I need some help! I was on my computer last night (windows 98) and the page started running slow. I decided to restart my computer from the start menu. It booted down and back up and usually where it shows my desktop there is a box asking for "user information" as if i were installing for the first time. It has never done this it is also asking for a "code" the serial number you put in when you install something for the first time. I have no codes and no installation cd because the computer was give to me for free. Is there any hope or is there anyway to get the codes?? Also, what causes this?? Please help! 
Welcome to Computer Hope! with your first post.
I see you are online, perhaps hoping for a speedy reply.
I too use Win98. However I've never had anything like what you've described to happen.
Hopefully you'll be getting some more replies from others with more specific ideas than I. In the meantime though, could you post back and tell us if you have, and use, any anti-virus software? same for anti-spyware software. If you do, are they up to date, and when was the last time you ran a full scan?
Also, try something. Can you boot into Safe mode on that computer? ( I'm assuming you have two computers, since you are here posting. )
For more info on safe mode, if you need it:
http://www.computerhope.com/issues/chsafe.htmJust want to be sure it will. Let us know. I think others here might be telling you to do some things that will require it.
You said you were "on my computer". What were you doing?.... anything different or unusual? visiting a new website? .... what?
Have you downloaded any software lately? installed any software lately?
Hopefully, with the information asked above, plus anything else you can think of now that you are in that frame of mind, someone will be along shortly with some ideas for you.
Again, welcome to CH.
