This is some standard guidance that addresses the most common reasons for Flash problems in Firefox:

(1) Make sure all recorders/downloaders that interact with Flash media are as up-to-date as possible, or disable them.

(2) Disable hardware graphics acceleration in Firefox and in Flash

(A) In Firefox, un-check the box here and restart:

orange Firefox button (or Tools menu) > Options > Advanced > General > "Use hardware acceleration when available"

(B) In Flash, see this support article from Adobe: http://helpx.adobe.com/flash-player/kb/video-playback-issues.html#main_Solve_video_playback_issues

(3) Disable protected mode (Windows Vista/7/8)

See this support article from Adobe under the heading "Last Resort": Adobe Forums: How do I troubleshoot Flash Player's protected mode for Firefox?

Hi Jscher,

Thanks for prompt response bt it is not helping.

Could you also try Firefox's Safe Mode? That's a standard diagnostic tool to bypass interference by extensions (and some custom settings). More info: Diagnose Firefox issues using Troubleshoot Mode.

You can restart Firefox in Safe Mode using

Help > Restart with Add-ons Disabled

In the dialog, click "Start in Safe Mode" (not Reset)

It might take a while to know whether there is any difference.

Hi,

Even in safe mode also it hangs, without flash player i cant see vids on youtube and other things also... Seems I have to switch to other browser :(

@ Mozilla Staff: Please help to fix this issue.

When it hangs, can you check the Windows Task Manager and check what you have listed on the Processes tab?

You can call up the Task Manager by pressing Ctrl+Shift+Esc

On the Processes tab, you should see firefox.exe and for playing Flash media, plugin-container.exe. With the Flash Player protected mode disabled, you should NOT see separate lines for Adobe Flash player processes.

Does the memory usage for Firefox or plugin-container on your system seem huge?

Sorry I have an issue similar to mentioned in topic. Sometimes I use two windows: one over other for watching IPTV another for surfing, and when I minimaze the latter (error occasionaly occurs) Fierfox hangs up. Now I perform an example and attach it a bit later.