Yeah, I'm using the OSIF on XP. I don't know about alternatives though. The OSIF test software was written on a Linux platform, and is cross compiled for windows. I've noticed that this software seems less stable on an XP platform. Can you try it on a Linux platform?
I found most of my scan bus problems were typically caused by the OSV3 board. I had one where the motor cap was shorted and would cause a reset when ever I told the motor to move. I've got one that resets for an unknown reason. I'd say take a close look at your OSV3 and make sure there aren't any shorts. Specifically the POT leads and motor driver cap. You did add the motor cap right? Also try different boards, if you have have a new board with out a motor and POT, give that a try as well. I've got one that seems to be just bad. Don't know why, haven't looked at it very closely yet.
Some notes, try using XP to flash your firmware. Don't try too hard, theres a problem with / vs \ in the file name. You can't open the firmware file on XP. It's a bug.
Also the software uses lsusb for the USB driver. I'm not an lsusb expert, but is appears that lsusb is less stable on a windows platform. I've had trouble with lsusb and windows on this project and other projects in the past. I've never had a lsusb problem in Linux, only windows. If you have trouble finding the device, you might find a reboot can fix your problem.
Here's a link where I documented most of my modification process. It's a work in progress, so don't take what's written there as set in stone, but does have a lot of useful information.