Just bought a BU-353 and waiting for it to arrive next week.
I have the BT-339 (Bluetooth) and have connection issues from startup mode, etc.
So trying the USB version. I'll let you know if I figure something out.
If yoy have a COM Port (9-Pin) on your Mobo, then I would try Changing the COM Setting of the GPS, if possible. (I do not know about that GPS receiver, yet) I can on my BT version.
Change the INBOUND COM Port. Put the OUTBOUND COM Port to something like COM8/COM9. This way it is out of the way of your Serial port(s). They use COM3 & COM4 - If you have 2 Serial 9-Pin Ports)