I'm having a similar problem with my new Epson 1240U Photo scanner. It's a USB scanner which stops working at some random % through the preview scan and also hangs the scanning application - ie the Epson smart panel software, any other Twain app and even Vuescan, which doesn't use Twain.
The scanner's light on the front flashes when scanning, but this stops and turns off when the scanning app hangs - or is it the scanner that's causing it? Or more likely the USB port and drivers?
My PC is an AMD Athlon 1GHz on a Abit KT7-RAID m'board and using the VIA chipset and using Win2000. I have installed all the VIA drivers and USB software and patches, but I have not found anything recent on their website - ie since March, 2000.
only rarely can I get a preview scan to complete, and even rarer to get a complete scan done more than once... and I can't seem to duplicate the working process. I've tried booting with the scanner's USB cable out, then plugging it in, plugging into different USB ports etc but it still stops at different % of the preview 100% of the time now.
I've even completely rebuilt the PC with Win95 and win2k again without success.
I've also tried some of the other responses to the original posting - to remove all USB hub and controller hardware and let the drivers be reinstalled after booting, but this didn't fix it.
Any other ideas please? I'm desperate and p1ssed off...