Brand new out of the box RX640 3-in-1 printer. If I cold start my equally new mac pro, I can scan fine. Soon as I switch users the 2nd user gets a message that the scan monitor was unable to start the scanner. Switching back to my account again, and I can no longer scan. Restart, and I can repeat it all over again. Tried stripping the Epson driver off the machine, reinstalled, and it fails all over again. Tried with the latest drivers from Epson. Anyone got any ideas? The scanner is totally useless to me in this state, and I'm not a Mac guru so unsure what to try next.