There is nothing wrong with either the software or the laptop.
I have a BU353 GPS and have no problems with it.
Make certain teh COM port that the GPS uses is set to 4800 baud, 8 Data bits, 1 Stop bit, No parity.
Are you using the prolific serial-to-USB drivers? If not, hunt them down and find them, or install from teh CD that should have come w/ your BU353. They're easy to locate on the web.
The last possibility is a faulty or non-working unit. If you purchased new, it should be under warranty.