Espon 1650 Photo Problem

Hi there, I am trying to digitally archive a bunch of negatives and I
am coming across a problem with the scanner. When I place a strip of 4
negatives, the scanner only 'sees' 3 and for some reason 1 of the negs
comes out a a very thin strip, rather than the whole neg. Negs are Fuji
400 taken in 1979, grease and finger print free.

I tried using Vuescan (unregistered) to see if it was a hardware problem
and the negs come out just fine. I installed V5.71 of the espon driver
and I still get the same problems.

Any clues what might be causing this ?

Thanks

-gk-