You can visit the "Adobe - Common Flash Player download and installation issues (Windows)" page:

http://www.adobe.com/products/flashplayer/support/index.html

You can find a link to download the Flash plugin for Windows in "3. DOWNLOAD ADOBE FLASH PLAYER".

For Firefox you need: Flash_Player_10_Plugin (All other Windows browsers)

See also:

http://kb.mozillazine.org/Flash
http://www.adobe.com/software/flash/about/

I have had this problem for just less than a year. I tried fixing it by uninstalling, reinstalling, deleting old versions, I even formatted and it still didn't work. So I just started switching to Chrome if ever I really wanted to use Flash on a web page. I did have another few go's when I had a spare afternoon:

http://www.adobe.com/products/flashplayer/support/index.html http://support.mozilla.com/en-US/kb/Managing%20the%20Flash%20plugin http://www.pchell.com/support/flash_player_will_not_install.shtml

However, I was just checking in with the BBC when Chrome notified me of an update that was needed for Flash player. I duly updated, I had to shut Firefox down while the process completed and for some reason, I just knew... When I fired up Firefox the first page I went to was BBC live and there was Flash playing away happily!

So it would seem the most simple solution to this problem is: Get Chrome!

I had this problem and basically nothing would fix it. I finally resolved it easily by copying the file npswf32.dll from "c:\windows\system32\macromed\flash" to "c:\program files\mozilla firefox\plugins"

I realize that this isn't the "right" way to solve this but it's the only way I could find. The biggest downside is that your Flash update will no longer work, so you have to remember to MANUALLY REDO THIS FILE COPY whenever Flash updates.

For future reference, I used this solution with Firefox 5.0 and Flash 10,3,183,5

I think this might have something to do with the fact that I have both Firefox and Chrome installed, but I'm not sure.

I managed to fix my issue on Windows 7 32 bit Firefox 6.02, same as the posters, Flash would not install in Firefox as a plugin, nor via the web installer, nor the standalone install EXE. The standalone would say it installed but it would not bother to tell Firefox.. The web installer just sat there spinning it's wheels until I cancelled the task after 5 minutes.

Deleted the temp files in C:\users\<username>\appdata\local\temp, nothing changed (the installer dumps an exe in there)

Ran the flash un-installer between tries. Finally I loaded up PROCMON and saw all these TeaTimer processes at work and it made me think that the resident virus scanner may be the culprit. I am running Spybot Search and destroy as well as the AVG Virus app. AVG has a resident scanner, Tea-Timer seems to be a similar sort of app bundled with Spybot search and destroy.

I stopped the AVG realtime resident scanner and tried to install Flash, no dice. I re-enabled.

I went to Spybot, unchecked the Resident protection option and BAM. Flash installed like a champ.

I haven't tested putting the Spybot Search and Destroy resident scanner back on yet but flash is working fine now.

Cheers!