projector sickness?

Something I forgot to mention is that I felt very sick during the OSHA training. The only things that were different was my caffeine intake and looking at a projector for long periods of time. I'm sure the caffeine didn't help, but I started feeling dizzy and lightheaded by the end of class on both days, and I think it was more the projector than the caffeine doing that. I get caffeine headaches, but they don't feel anything like what I felt on those days.