Getting Error "Serial port 'COM38' already in use. Try quiting..."

Hey

Im a newbie to this field, i got my self a MultiWii SE 2.5 with a FTDI to begin. But now when i try to upload the code from arduino IDE i'm getting the error "Serial port 'COM38' already in use. Try quitting any programs that may be using it."

I have been trying to Solve this error for over 2 days now. Please Help Me : /

Other Info: Running Windows 8
using arduino-1.0.5-r2-windows
trying to upload MultiWii_2_3

Please Help :frowning: