When mousing over links in Firefox, the arrow cursor icon changes to a hand icon, at least on my Mac. Since FF12 or FF11 or so, mousing over links sometimes does not change the cursor correctly. To fix this, I move the cursor outside of the Firefox window and then back again, and it's fixed.
I tried disabling Hardware Acceleration to see if that fixed the problem for me, but so far I think I've noticed the problem even with Hardware Acceleration disabled. I also actually think I might have seen it on another computer as well, when no extensions were installed. Odd. Perhaps it's a "Firefox on Mac" problem?
I think I noticed that this cursor problem happens when a page is loading and my mouse happens to be on top of a link that appears underneath it. So then the cursor doesn't change because it was in that spot when the link appeared below it, so then the cursor never changes to the hand icon until it's "refreshed" by moving to outside of Firefox and then moving it back to Firefox.
So, anything else I could try to fix this problem? I know I could perhaps try in Safe Mode and perhaps I'll try that, but the problem doesn't happen all the time, and of course it happens at unpredictable intervals.