Not able to access income tax efiling website

In our office we have 3computers. I couldn't able to access the Income Tax e-filing Website in two of my computers. Only in laptop i can access the Income tax E-Filing Website. In 2Computers we have windows XP & in laptop we have windows 7. Is there any new conditions were we can access Income Tax E-filing website only in Windows 7, even in my home i have windows 7 i can access from there