I have a GPS from u-blox.com with a USB-connection and driver. The driver installs a virual COM port that pops up when you plug the USB in. Using a hyperterminal I can then
I have sucessfully used the SerialPort class in .Net 2 also with gps on a virtual comport. It seems your virtual comport driver is slightly off. If you can't locate a newer driver I would suggest you call the WinAPI functions for reading the serial port.
Take a look at this code for instance: http://www.codeproject.com/KB/system/SerialPortComm.aspx