Agree with devnull. There are a lot of BlackBerry users and on forums you mostly only hear about the problems, not the successes.
Take a look at the following two articles. Is your BlackBerry Nuked - BlackBerryFAQ What to do next if Jl Cmder will not connect and wipe - BlackBerryFAQ
Pay attention to the step involving getting the BlackBerry to connect the instant the connection display in the application loader wizard switches from COM1 to USB-PIN:UNKNOWN (or USB:BBPIN).
These articles do not specifically apply to your problem, but the method of making the connection may be your solution, if there is no other problem with the BlackBerry or the desktop computer.
So, give it a try. Note that timing is important. If you don't get it first try, try again and again a number of times before giving up.
Good luck. Posted via BlackBerryForums.com Mobile