Disable RAW in the port. (If the jobs were using IPP or LPR they would show the Windows User and the filename)
Could be a virus, could be a reporting software outputting incorrectly to the printer port. Could be many things.
But by far the easiest method (if it constantly keeps printing is to unplug the printer from the LAN and wait for the PC sending the corrupt job to fault it. Or as stated, remove the RAW port from the printer so it stops being able to even try anything coming in RAW.
You may have a few users intentionally printing using RAW instead of LPR, you would need to fix those PC's when the complaints come in.
