Arduino Mega 2560

I am having upload issues. Working on windows 7. Drivers are up to date. Either It never uploads or it gives me this message

Unknown status 0xc8
initialization failed, rc=-1
double check connection and try again, or use -F to override this check.

.... Failed to leave programing mode

I would overide the check if i knew what using -f meant.

After I move to the right prot I get COM 6 already in use.

Ever connect a PDA or mobile phone to the computer?