Of course Mozilla fire fox because I have been continuously work with it around last two years. But I had seen not any problem in before and now in a day.
I just perches new brand PC for my bedroom. I have to do use on 64 bit windows 7. first time was just installed 2GB RAM in it so some time my PC was going to hang so after then I install 4GB RAM on in it. Right now my PC is working very properly.
This is a wonderful browser. I have been use this one around three years in my PC. Its having a very nice feature to compare with any other browser. I was just wondering first time i used ADD-ON feature in IT.
I think you have just missing some task bar related file so keep catch from the system 32. Otherwise your PC having a virus so may be this become a problem. so formate your PC with license version anti virus.