Just loaded CS5 on Mac 10.7. I downloaded and installed the latest OSX Epson 1640xl scanner software, and also copied the Twain plugin from the Adobe Goodies CD to the Photoshop > Plugins > Import/Export folder.
Rebooted the computer, power off and unplugged my USB scanner, fired it back up, restarted Photoshop, etc. It no longer shows up in Photoshop>File>Import
But Photoshop doesn't see my scanner at all. In fact, the TWAIN plugin doesn't even show up in the plugins folder list.
Little Help? How do I fix this? Everything worked perfectly with Mac 10.6 I also took the scanner into a epson dealer and the scanner works perfectly.
You need to run Photoshop in 32 bit mode to see TWAIN devices.
That scanner is sort of old, and doesn't have a 64 bit driver.
As Noel said: use Photoshop in 32 bit addressing mode to work with older drivers and plugins.