well you have to download it to your pc, then close all of your browser windows completely shutting down all instances of firefox, then go to the download and double click to begin the install, follow wizard. to see the plugins you have in your firefox browser open a firefox browser window, in the url box type about:plugins and hit enter, it will give you a list of all current plugins and their state. A really good free little program by Secunia will tell you if any of the programs and such are up to date or if there are newer versions, it is very helpful to keep things updated. Here is a link that might be useful: secunia personal software inspector

It looks like I got the problem resolved. I used REVO to totally remove FF and all references to it, including personal settings. I opened I.E and browsed the web and all worked well. I.E. is using the FIREFOX version of FLASH PLAYER 10______.34 which I manually installed into I.E. and it accepted. I then ran the install for FireFox 5.0 As it was loading it asked me if I wanted to import settings from I.E., I opted YES, I was then asked if I would like to make FF my default, I opted YES. Once done and without making any changes or additional additions or actions of any kind, FF imported everything I had in I.E. I went to several sites I knew Flash Player would be needed and everything worked fine. It appears as I suspected, there was a toggle somewhere in FireFox that got toggled to either TRUE or FALSE. I wish I could have determined which one, to have made this problem go away sooner. If time permits, I may play with them until I can recreate the problem. Thanks much to all of you who responded and were so willing to give up your time and effort to help me.

CBS had not manifest the problem. Wife was watching a rerun of of 48 hours clicking back an forth between full screen and not full screen and got the 'Abobe has crashed message'. Went to IE and could not repeat the problem. Firefox and F11 back and fourth only causes the problem on ABC and occasionally NBC/Hulu. ABC never works with full screen. So it seems to be Windows 7, Firefox 13.0.1, Adobe Flash 11.3.300.265 and ABC with occasionally NBC/Hulu. This computer is used for Netflix and Hulu so we can live with the problem but its still curious.

Each browser must have its own flash install and you must get, download, install the specific version for the browser you are using. So for firefox use firefox to download the firefox version of flash, install, for IE go with it get the ie version and install. I generally get the flash at filehippo just search for non ie flash on Google. I would suggest adding the adblock plus add on with the easylist subscription to block the ads which will help speed page load quite a bit. Definitely make sure that your adobe products as well as java are fully updated and it is essential to remove the old versions just having them on the pc leaves the security issues there. Go with each browser and update.