silvermel causing crashes in Firefox 18 - Silermel addon was the problem!
Firefox 18 was constantly crashing whenever I would close a tab - even in safe mode. Scanned for malware using MS Security Essentials, Malwarebytes, Super Spyware, Microsoft Windows Malicious Software Removal Tool - nothing found.
I removed addons one at a time until it didn't crash upon exit. Turns out my Silermel addon was the problem.
Wšykne wótegrona (1)
Silvermel is not yet compatible with Firefox 18. It's normally disabled by Firefox, unless you manually disabled compatibility checking using a hidden preference or an extension.
It's always best to report problems with specific add-ons to their authors. Most add-ons have either a "Support site" or "Support e-mail" link on the right side of the add-on's details page. The add-on description might also list the best way to get support.