QTR-Quadtone RIP

I have just started evaluating QTR by installing on my MacPro running OsX 10.6.8 with 16GB ram for use with an Epson 3880 connected via Ethernet.

I made three prints using it then decided to make the same prints with the regular Epson driver with the printer in ABW mode so as to do a side-by-side comparison.

I am no longer able to print through the Epson driver. I look at the print queue and momentarily see a "printing" message but one or two seconds later the print queue closes without any indication of an error. Meanwhile the 3880 seems oblivious to anything going on.

I downloaded and re-installed the latest Epson 3880 driver, rebooted the computer, but the problem remains.

Any help would be greatly appreciated.