Hi pclind, this is probably related to extensions. You can try it out easily by starting Firefox in Safe Mode. Here is how: Troubleshoot Firefox issues using Safe Mode
It could also be the Java Plug-in. I'd just disable Java, if you don't really need it, most people don't. Here is how: How to turn off Java applets
Hope that helps.
I tried the two suggestions. Turning of java didn't make any difference. But running in safe mode with no plug-ins did work. These messages popping 4-6 times every time a page is loaded, started when I upgraded to beta 17.0 from the previous beta release.
If it does work in Firefox Safe-mode then disable all extensions (Tools > Add-ons > Extensions) and then try to find which is causing it by enabling one extension at a time until the problem reappears.
Close and restart Firefox after each change via "File > Exit" (Mac: "Firefox > Quit"; Linux: "File > Quit")
I was having the error Java Error message: evalInSandbox:SyntaxError: syntax error. Social Fixer has it corrected in version 7.301, and I am using Firefox 17.0 beta with Social Fixer 7.301 and not having any more of the errors.
I get the huge wave of Java messages since I upgraded to 17. Tried to revert to 16. That didn't work. I don't have SocialFixer Installed, or at least it's not in my add-ons list. And now I can't run except with all add-ons disabled.
Looks like it might be time to switch browsers again.