Green Giant,
1) Uninstall Smog drivers. Delete the rest of the files that are in the driver install folder.
2) Try to install the Smog drivers previously to connect any LCDTopGun. (Install the drivers without any LCDTopGun connected).
3) Connect the gun that doesn't work.
4) WindowsXP must recognize a new device and must install two drivers: a guncon2 driver and a generic mouse driver.
At his point, be sure that the Leds bars are connected to the gun installed to give them the power that need to work.
5) Probably you will need to make a hardware calibration. It is a hardware calibration, not a software one. So, really, you could do this hardware calibration before. It is only necessary that the gun and the Leds bars are connected. Nothing to do with the Smog Drivers.
6) After this, you could track the mouse cursor with the gun.
7) Connect the other gun to other usb port. Windows must recognize like the point 4. If it does not, retry the connection or change the port.
Continue with the point 5 and 6. The second gun also tracks the mouse cursor.
After this, you can open the guncon2 control panel to change the button configuration.
Don't use the recoil function of the LCDTopGuns. They consume a lot of power. Maybe the problems with the boot is related to this. Try to connect the guns to other usb ports and check it.