Ever since I installed the new version of flash 11.5 I have had major issues with watching video etc. I am also into astronomy. Myself and many others have paid a lot of money to use Sloohs robotic telescopes in their canary islands observatory.
I now cannot enjoy this because the flash player has compatibility issues with your browser. Me and quite a lot of others are getting rather annyoed this opportunity is being ruined because adobe have released a version of flash without checking it's compatibility with all browsers first.
May I suggest that you contact them and ask that you are notified about new versions and release dates to ensure that you can make necessary amendments to prevent incompatibility issues.
That way lots of angry people like me will not be complaning.
First, please update Firefox. Update Firefox to the latest version.
Then, for the Flash issues, we've done all that can to ensure that Firefox is compatible, there are some issues that Adobe still have to work out and we are in communication with them. You an try some of the steps in Flash 11.3 doesn't load video in Firefox if you'd like.
Firefox is pointless. It updated to 18.0 today, and now it won't recognize any flash below 11.5, but it won't work with 11.5. It just freezes completely after opening. I had 11.2, but 18.0 won't allow you to use it at all. 11.3, it won't allow. 11.4, it won't allow. Upgrade to 11.5, and it just completely freezes. Clearly mozilla never fixed this issue. Going to IE9.
At work, symantec endpoint. At home, norton. Ever since firefox 15, no flash version works except for 11.2. Now that ff18 was pushed out, it "forces" the upgrade to 11.5, and absolutely will not accept anything less. But as with any version of flash that was not 11.2, it just causes firefox to freeze up completely.
this is likely due to the protected mode that adobe has introduced to its flash plugin for firefox since version 11.3 - when there's an interference between the sandbox of the flash plugin and the firefox main process it might slow down things considerably or make the browser hang (i've experienced it myself, however i don't use norton so i can't give any advice to change any specific settings in it or know if it is causing the problem).
firefox should only block:
i tested it with firefox 18 & it worked for me when i downgraded to flash 10.3 from the link (which results in version 10.3.183.43 once installed). what is the exact error message in your case & where/when does it appear?
maybe the blocklist file got corrupted - in this case go to firefox > help > troubleshooting information and click on profile folder/show folder. a windows explorer window should open up - in there delete the file named blocklist.xml & restart firefox afterwards.