Had the oddest thing happen today; The spacebar and option keys stopped working while I was using Illustrator CS4. I did a little searching and testing and found that Firefox (v3.6) was the culprit. I quit FF and the spacebar/hand tool/option keys were back! I was able to restart Firefox and everything is still working fine with both programs running. I’m sure other programs could cause this issue as well. Odd bug that can drive you crazy. Makes you realize how important that little spacebar is.