Vertical rolling lines with DSLR and projector

Question

I used a DSLR (EOS 60D) as a B camera for wide shot on a shoot in a dark lecture room the other day.  Vertical rolling lines were evident across the whole frame.  Whilst similar to scan lines on a CRT the lines were not restricted to the projection display.  I assume this is related to the shutter speed, but whatever speed was selected I could not get rid of the artefact.
Are there any post production solutions for this?  Forunately I used another camera ( a proper video camera ) for the A roll and had much more control over the shutter speed.  The B-roll is not crucial but would be useful.
TIA

Answer 1

Thanks for all the responses.
There was daylight from the right side of the room but the lights were down.
I think that as suggested the problem was a mismatch between the projector and camera.  Unfortunately whatever shutter speed I used on the DSLR the problem was evident (another "I don't believe it!" moment) .  I wonder if the projector was a DLP unit and the problem was the combination of wheel rotation on the projector and shutter speed on the camera. I could adjust the camcorder's shutter speed far more precisely than the DSLR's, so I am glad not to have had to rely on the DSLR as the only camera.
I was hoping that there might be a way to fix short sequences as cutaways, but maybe not.
Andrew