Instead of going through this repeatedly without any luck, you can simply install the plugin manually with a couple of steps.
Note that you can use this manual method to install any plugin, not just Flash.
Install Flash Plugin Manually on Vista
The first thing you’ll need to do is manually download the plugin file. You should be able to right-click on this link and choose “Save Link As…” from the menu.
http://fpdownload.macromedia.com/get/flashplayer/xpi/current/flashplayer-win.xpi
Once you have the file downloaded, rename the file with a .zip extension:
You should be able to double-click on the file to open it up, since .xpi files are really just renamed .zip files.
Now you’ll need to copy two files from that directory into one of two directories, depending on whether you want to install the plugin globally for all users, or just for your user account.
The two files you’ll need to copy are these:
flashplayer. xpt NPSWF32. dll
Install for All Users
Navigate down to the following path in Windows Explorer to find the Firefox installation directory:
Note that if you are running on 64-bit Vista the path will have (x86) like the next screenshot, or if you are using Portable Firefox you’ll have to find your Firefox installation folder and navigate to the plugins directory there.
Now paste those two files that you extracted into this directory (You’ll be prompted by UAC), restart Firefox and you are done.
Install for Your User Account Only
If you don’t have administrator access to your machine, or you simply want to install for only your account, you can browse to the following path:
Once you are in that directory, create a new directory called Plugins if it doesn’t already exist:
And then paste the two files into the Plugins directory. Restart Firefox, and you are done.
Verifying Installation
You can make sure that the plugin is loaded and turned on by typing about:plugins into the address bar:
Of course the simpler test would be to just load up whatever page you were on before you started troubleshooting. =)
