Mozilla Avast tab open automatically

[yousquilez]

Since 2 weeks, every time i open my mozilla firefox browser, there is 2 tab open. The first one is Google (i want this one) and i got a second tab Avast (security) and if i go into my options browser, my homepage is set to Google and i can't see avast to stop hit to open because i didn't need it.
Thanks

[Eddy]

Please use the search option on this webboard before posting.
This issue has been addressed many times before.
Here is just one of the many threads about it :
http://forum.avast.com/index.php?topic=148337.0