Running WinXP on a Toshiba laptop, I installed a USB to Serial (DB9) cable (Prolific)- and hooked a magellan gps to it. I used the driver CD that came with the cable.Originally, it installed to Com Port 3. Initially, when I turned the GPS on, it started sending wild commands to the screen, with the cursor jumping all over the place. I reconfigured the port at 4800 baud, went to a Xon/Xoff handshake, all other configs pretty standard. Also set the GPS to the same baud rate and set the NMEA. I was able to get the thing to work several times, (essentially sending GPS coordinate data to a mapping program) but over the weekend, my son signed on to the laptop with his own account and it attempted to load the drivers for the USB cable again - and the GPS would not work. Anyway, to make a long story short, I deinstalled and reinstalled - now I get the blue screen of death, with it saying that there is a device conflict with ser2pl.sys, irql_less_than_or_equal. Like this other user, I can not reboot - I need to turn system off and then on. What I would like to do is get back to square one, and reinstall all over - however, I tried a deinstall and reinstall in the hardware driver screen for the USB Serial device under COM/Printer ports - something on the system is now hosed up so that it does not work after the reinstall. One other thing: the system did not blue screen until I turned the GPS on, and the GPS started sending data down the line - its seems as if something was already sending data, possibly to that interrupt and didn't like a second participant. Any help would be appreciated.