Hmm, my first guess would be that your Serial port got rerouted, or else it got disabled somehow. Can you check both in Device manager, and your computer's BIOS settings?
1. Right-click on My Computer (or just Computer in Vista)
2. Select Properties
3. Click Hardware tab.
4. Click Device Manager Button.
Look for anything disabled there - if you don't see anything disabled or with a red exclamation mark or a yellow question mark, then this probably isn't the problem. However, while there, just look to see if a Serial port is even listed.. if it isn't, then that piece has died, or else it's been disabled in the BIOS settings - most likely. Of course, it could have been removed, and never reinstalled - again, not likely if you're running XP or Vista, and haven't disabled the Plug and Play service.
1. Restart your PC
2. When the computer is just starting up, you'll need to be pressing one button.
a. If a custom built machine, most likely it's <Del>
b. If a Compaq or HP, then it could be <F11> OR <F10> I think.
c. If a Dell, it's either <F2> or <F12> - I think...
d. eMachine is usually <Del> - again, if I remember correctly.
If you see anything about "press... to enter setup" - then THAT's the button you need to press.
3. Once into the BIOS, you'll commonly have a blue screen... or else a gray screen... or possibly another color (I know my Abit AB9 Pro board has a pink BIOS screen - probably the most annoying thing about the board.
4. Probably under "Advanced" or "Onboard ..." is where you'll find your Serial port info - it'll be set to some series of letters/numbers or else Auto or else Disabled. If Disabled, that's your problem. You need to change it to Auto, or else one of the other options - frankly, I've not needed one that I can remember, so I've not really looked up what the different settings mean.
"If to err is human, then I must be some kind of human!" -Me