CSS cursor pointer flicker once and then back to default

I don't believe you need to restart your computer for this. The issue is actually when Photoshop is open at the same time as your web browser. For some reason this creates the issue. I imagine it has something to do with Adobe and Apple not playing nice. If you close photoshop the issue should resolve. Rebooting the computer only appears to work because you likely closed your programs before doing so.

Maybe the element position is changed very subtly when you hover on it, causing it to rapidly switch between hovered and unhovered state, then the CSS cursor is switching too.

Try giving it a position relative or absolute :)

This sounds like a ridiculous answer but I had a similar issue on Mac OSX (any browser). I've noticed the problem wasn't in my code but on other web pages too - like this one and a simple system reboot solved this.