I've updated my Flash plugin for Firefox a few days ago. There seems to be major changes in this new version (11.3.300.257), including the fact that there's one installation kit for both 32 and 64-bit operating systems.
After a few hours I've noticed that my browser window focus was stolen by something when I loaded certain pages. After a couple of tests, I noticed it only happened to Firefox. But that's my main browser and having the window focus stolen is one of the most annoying problems in Windows.
Anyway, to cut it short, I arrived to the conclusion the culprit was the new Adobe Flash plugin version. Me and a few others seemed to have the same problem. Here's how I solved it on my Windows 7 64-bit Professional:
1. Uninstall Flash from your computer:
- download the official Adobe Flash uninstaller
- exit all browsers and other programs that use Flash
- run the uninstaller
- delete the contents of the following folders:
2. Install an older version of the plugin - I chose 11.2, since it's worked just fine till the update
- search for install_flash_player_11_plugin_64bit_188.8.131.52.exe (or the 32-bit version if you're on Windows x86)
- run it and install Flash 11.2
3. Enjoy focus-stealing-free surfing!