That's theoretically possible, but photosensitive epilepsy (to which only a very small percentage of the population is susceptible) is generally triggered by cycles of around 4Hz - or 4 times as fast as my macro updates - and typically involves red flashing. So, provided you avoid red-spectrum flashing with cycle times approaching 4Hz there shouldn't be a problem.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]