Invalid system disk error...

Okay, so I have a friends old laptop that has Windows 98SE on it. After attempting to install some USB drivers so that a pen drive will work my friend tells me that the laptop won't boot into Windows. It gives the error from the Topic Title. So I have booted up using a W98SE boot disk and did SYS C:. It said the system was transferred so I rebooted. Now I don't get the error message but very quickly after the 98 splash screen pops up it goes to a command prompt (C:\>). Is there a way to get back into Windows without reinstalling the OS? If not, is there a way to get the CD Key from this DOS environment with some DOS based tool? Let me know what you think. Thanks.

 

Yeah, you can get the key, but all I can give you is hope right now. Can't remember how you get it . . . but it is there. I start looking for it. Be patient, please.

 

I decided to just install 98SE over itself and that fixed the problem.