Nope. Wrong advise guys...

Well.
No need to uninstall Mozilla
Just go to your PC's "Control Panel"
Open "Regional and Language Options"
you will see a pop up with 3 tabs
Regional Options |Languages |Advanced

Go to Advanced tabs you will notice that the default language there is Arabic... so Change it to either "English(American)" or "English(United Kingdom)"
Click ok when you finished.. I think it might require a system restart and when it reboots your problem will be solved..