In november, when the firefox was updated automatically (as I remember for v.33.) I normally used my firefox browser, it was closed from itself without any error message, i did not do anything. Since, then I could not open my firefox. I re-installed more times, I tried to used earlier versions and also the newest one. But they are also not works. I deleted every related files from the windows registry. It did not solved the problem. Today, I read an article, If i press the shift button while opening firefox, it will run in safe mode. Okay now it is working. But if I would like to use in normal mode, it is not work. How can I use my firefox browser in normal mode again? Some addtional information: I deleted the old firefox data, but the process can not be fully executed. I switched of the hardware acceleration. I have win 7 64 bit system on an asus computer with 6 GB memory and i5 CPU. Thanks for every advice. Zsuzsi