My coms port seems to be used by another program, but i have only the arduino IDE run with no other device plugged into my computer.(Windows 7) It has been working but now I seem to have a problem with uploading. Can any one me with this problem??
Have you ever connected a PDA or smart-phone to your computer?
Read a while ago that bluetooth on laptops can claim a lot of comports.
Check if BT is switched on or optionally uninstall BT drivers. ?