Firefox may not have closed properly. Go to File | Exit and give it a minute or two before you try again.

It's a good idea also to uninstall the existing copy first using Adobe's uninstaller which you can download from Flash Uninstaller Be aware though that running it will also uninstall it from IE8 (or 9). So you'll have to download it again using that browser if you use it as well. You can however perform the installation from within IE.

Reboot before you run the installer for Firefox in any event though.

One other tip. If you watch youtube videos, you can signup to the HTML5 trial just by clicking the link on this page: http://www.youtube.com/html5 (nothing to install and no forms to fill in).

There's a sample html5 video @ http://videojs.com/

i tried that and it didnt work ! I am afraid if i uninstall the old version I wont be able to download the new 1

Removing an old version of Flash doesn't interfere with installing a new version.

I perform that step myself as a matter of course to eliminate potential installation problems.

Just make sure you download the new installation file before you remove the old one. You can get that from http://get.adobe.com/flashplayer/

4 step:

first step: remove firefox(completely)

second: remove Flash player

third : Install firefox

fourth:install flash player(not beta version)

let me know the out come okay? :p

Skip the first step. You don't have to remove Firefox, just the Flash player.

I am afraid if I remove the old version and the problem is still the same .. meaning I wont have any version of flash player .. will that affect my video viewing on the internet .. not having a flash player ?

If you remove the old version with the Adobe uninstaller, you will have absolutely no problem at all installing the new one, I assure you. I do it all the time.

You can also simply go to http://www.adobe.com and click the link to Flash player and install it that way too if you wish.

Without Flash installed though, you cannot watch Flash based videos.

I had to uninstall firefox then update the flash then again install it again even the the uninstaller wasn't working but its fixed now !

Sounds odd. Why did you feel it necessary to uninstall FF if you don't mind me asking?

well I was on a site that asked me to install flash even its suppose to be working so i tried the same site on the google chrome and it worked just fine so I thought there might be something wrong with the firefox .. so I uninstalled it after i installed it back i tried the flash installer just to check and the problem was solved .

Interesting solution anyway.