Hi Brad:
I have almost the exact same config as you do, I have  a 2940UW, to connect a
zip plus and a Hp6200C together and had massive trouble with it, but i did
manage to make it work...Here's what I did...
Go into Adaptec BIOS (control +A)
Turn on SCAM (the plug and plug thinge for SCSI), my 6200C supports it, dunno
about the 4C (the SCSI ID selection settings  seems to be stuffed in HP
scanners, it appears that the BIOS thinks its 0, and the OS thinks its whatever
you set it, so SCAM is the only way around it)
Try Setting the termination to Auto (My scanner didn't like the other settings)

Before going onto the software side, make sure the 2940 detects the scanner
(should have a star next to it)

Make sure your ASPI is installed correctly by downloading ASPICHK and ASPI32
from http://www.adaptec.com/support/files/upgrades.html

if it still won't work, find and delete these files twain*.* and twunk*.* then
reinstall the software..(you did obtain the new drivers from HP right?)

Hope that helps,
Alan Liu

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