Adobe Flash Player 11.7 Will Not Install - Times Out at 47%

I am running Windows 7 Home Premium Version 6.1 on a 64 bit HP desktop. Primary browser is Firefox 21.0. Have been trying every way I can possibly think of to install Adobe Flash Player 11.7 without success.

Have followed the steps on the Adobe site very carefully. Uninstalled old flash, restarted, removed leftover old flash files. Then run installer for latest version for Windows 7.

I use Trend Micro Titanium Internet Secrity 2012 as my virus protection. Have also tried doing all of the above with Trend Micro not running at all. Still no success.

The same thing happens no matter what I do. The flash installer goes to 7%, then times out. It shows 47% complete when it times out.

Can anyone help me? Right now, there are key sites I use that no longer work AT ALL without the latest version of flash.

Thanks in advance.

Cheers,

Corinne