Bug with Firefox

When I run the cleaner it now deletes all of my tabs I had open before

I closed Firefox. It didn't used to do this and it's really annoying.

New in CCleaner v2.35.1219

?Added Session Cleaning for Firefox and Google Chrome.

I don't use Firefox but maybe there's a check box you could clear to prevent this.

That is session cleaning. Its a new feature in 2.35 and can be disabled by un-ticking the "session" box under firefox in the applications tab.