btw, he added some more notes to his original post
http://www.mame.net/cgi-bin/wwwthreads/showpost.pl?Board=mamegeneral&Number=165840&page=0&view=expanded&mode=threaded&sb=7#Post165840I'm not sure what those combinations are that you're referring to. Basically, it's going to work best if you only have two usb mouse devices connected -- the lightguns.
Here's my config exactly:
WinXP Home SP2
2 Act-Labs PC USB lightguns (Not TV version). You have to daisy chain the boxes together. i.e. Gun 1 VGA plugs into Gun 2, Gun 2 VGA plugs into the computer, both USB connectors plug into the computer.
Mame32 v.89
This is running on an Athlon 2400 computer. It has 2 USB keyboards plugged in (iPac and regular keyboard), and has an optipac plugged in via the serial port for a trackball as a mouse.
Control Panel -> System -> Hardware -> Device Manager
Under "Mice and Other Pointing Devices" I had four entries. One was the Optipac serial mouse, and three were generic entries for USB human interface devices. I couldn't tell which two of these three corresponded to the guns until I went into properties for each and saw that one had a "Power Management" tab in the properties dialog and the other two didn't. I assumed the other two were the guns, and installed the CPN mouse driver for those two devices by following the directions on their site. (Right click the mouse in device manager, properties, driver, update driver, etc.)
After installing the mouse driver for both guns, I fired up Mame32 v.89, went to the controller options dialog, checked lightgun, dual lightgun, and offscreen reload, then started up Area 51 and Police Trainer and everything was suddenly working!
Give me more specifics on your setup / symptoms and I'll see if I can help you figure it out.