Virus that affects firefox?

Just now when I opened by browser i noticed that my firefox browser gave me a security message saying that the page i have opened is encrypted. This was the first time i seen this message in a while, so i went to my bookmarks to check for updates at my usual sites only to find that the bookmarks are gone, my homepage was reset to the default, and my cookies and history has been deleted. I have looked everywhere and there were issues with bookmarks being deleted but not history, cookies, and homepage. So I was wondering if this is some kind of virus. This has happened on my other hard drive as well. Is this a virus that has infected my browser to steal my information or something?

Dear Sir; Did you use a disk cleaner before this happened. If you did then that app may have deleted those things. A good idea is to use MozBackup. It will backup your firefox bookmarks, settings, profile, etc. I have used it for a long time and it works very well, at least on my machine. Always be careful how you use a disk cleaner. I used RegSeeker wrong and had to reinstall my OS. Good luck and have a nice day.