What issues are you having with Firefox 15? There aren't really any known issues in Firefox 15 itself (there is one with Flash 11.3, but that affects all versions of Firefox and there isn't anything we can do about it). So I'd suggest you update to Firefox 15, try it out and if you have issues, post where what they are :)

My problem with firefox 15 is that it keeps crashing Flash plugin 11.4.402.265. And before it crashes it acts like it is loading it multiple time (it will show two separate lines for the plugin in Task Manager. Also, the icon for FireFox on the task bar will get dark and light over and over again while you get the spinning wheel. Restarting Firefox will solve the problem for a short time and then it returns. Uninstalling the plugin will also solve the problem but then, of course, things on the we page won't load.

Ah, that is a problem that has been ongoing with Flash. try disabling protected mode and see if that helps. (Last steps on this article, ignore the other solutions) http://forums.adobe.com/thread/1018071?tstart=0

Tyler, I'll look at that article however, I wasn't having any trouble with FF 14. My problems started when FF decided to update itself to 15 a couple of days ago.

Solved. Turns out every time I upgrades Firefox the flash player would update as well. My computer was trying to think for me and doing what I didn't want it to do. Thank you for your help. I have games that I play. The play one game won't let me play unless I upgrade, the other game won't play at all. I thought the problem was Firefox because of the constant crashing.