Missing Cursor on Firefox

Question

I am running Firefox 3.0.4 with Windows XP. Recently, my cursor has started to go missing. It will completely disappear, and I'll only be able to locate it by typing something. I can't detect any pattern to when it happens.I noticed the same problem while using Firefox on my friend's computer which runs Vista, so I'm pretty sure it isn't an issue with the OS.Has anyone experienced this and knows of a solution?