These crashes are tagged with the Norton Security crash and the last conversation was in mid May. Can you disable the Norton Security Toolbar temporarily in order to make sure that 1 this is the correct issue associated with these crashes and 2 to see if this can still be treated as a work around. (This will help you and other users)

• http://forums.comcast.com/t5/Web-Brow.../2510705

Also the second crash, run a malware scan just in case, with multiple scanners:

• Troubleshoot Firefox issues caused by malware

symhtml.dll is also part of Norton software

• Firefox 38.0.1 Crash Report [@ symhtml.dll@0x3f36b ]

• https://www.google.com/search?q=symhtml.dll

Did you make sure via Norton Live update that you have all the updates for your Norton software?

Download the current full installers for your Norton programs and save them.

Download and run the Norton Removal Tool to uninstall your Norton product

After rebooting the computer, run a registry scanner. Then run the installers.

https://support.norton.com

http://community.norton.com/