Update: I just tried printing with QTR from a different computer (my laptop). The printer still makes a single pass, then stops and gives the error. I then tried printing the same file from CS6 and it prints fine on the laptop.
Next, I bypassed the spooler and clicked "Print directly to printer" from the printer preferences. Still no luck.
Something about my printer has suddenly stopped liking the files sent from QTR. Has anyone ever seen this?