Digital BW, The Print

I have a very odd issue. I'm printing some files on my 3800 a bit larger than I usually do, all of them 17" wide. However, the 3800 now most of the times (the strange thing is: not always) does not print the full width of the image. It leaves the left side blank. The other odd thing is that the white space is not always the same size, it varies.

I've tried a lot of different strategies. 
- I started with layered 16 bit B&W TIF files. Changed to flattened to 8 bit B&W files (all QTR-gray profile). Seemed to help in the beginning, but issue re-appeared
- First thought it was a QTR issue, but same thing happens printing from photoshop and qimage via the epson driver
- Tried with two PCs, Vista 64bit and XP 32bit, issue remains.
- switched on and off the printer several times to reset it, issue remains

I've no clue and I'm out of options. And an exhibition coming up in four days..... )-: Adrenaline is pumping.... Any suggestions??

Joost