Windows 7 - Can not install Windows Flashplayer

Hi,

        My system is Windows 7.  My computer is a Dell.  I have Flash player working perfectly in Google Chrome.  However, for work purposes, I must use Firefox.  Every time I try to install Flash Player for Firefox, it stops at step 3.  I get a BLANK page pop up.  Internet Explorer opens when I close the pop up and then Internet Explorer is BLANK too.  What can I do to get Flash Player to work in Firefox.   I would appreciate any help at all, this is for work purposes.

Thanks,

Helena