Right, I think I have reached a solution to getting reasonable prints again. What seems to work best is to print from lightroom 1.4.1, but using printer colour management and ICM in the printer driver. The quality still isnt quite what I'd expect though, but pending custom profiles, which seems the way I'll have to go, it'll have to do.
Mind you, I think this printer is beginning to show its age - this is the second time this year I have had problems with it, and the cut sheet feeder is no longer working smoothly.
I'm still at a loss as to what went wrong - it quite happily printed 20 images on hahnemuhle bamboo paper, 3 on hahnemuhle photorag, then suddenly went haywire.
Thanks everyone for your help. I might be shopping for a new printer later this year!

I had a look at these fancy papers you are using Gordon & can see why you wouldn't want to be wasting any

Also it came up with this The Roger Maile Colour Calibration CD - The DPA Print Tuner (MAC & PC Compatible) at £13.50
http://www.on-linepaper.co.uk/acatal...NE_Papers.html
which sounds as if it might be the sort of thing that could help
tho if the performance is erratic, maybe you are right and you are pushing the machine too hard for its age

Thanks for the link Chris - that looks useful

An update: I have talked to Epson technical support - excellent service by the way, and not too long waiting in telephone queues. They helped me through the process of checking the printer functions. The upshot was that the hardware was fine, and the problem was most probably down to a problem of the various generations of software not being quite in tune with each other. So - the recommendation was to update the drivers, update to CS3, and disable colour management in the printer. I have done all that, and also bought a profile maker and made a custom profile - so far only for the hahnemuhle bamboo paper, but the others will get done too.
The good news is it all works fine now, and at about £200 less than a new printer would have cost me.

Looks like you've done all the tests to find the bug but it is still faulty. So it is time to change your printer I think.