There are a number of active threads concerning the latest Flash player plugin (11.3) and the latest Firefox (13). Not all users are experiencing the same issues, but things to check include the following:

- Conflict with Realplayer Browser Record plugin (to disable this, open Add-ons from the orange Firefox button or the classic Tools menu and look under the Extensions and Plugins categories)

- Conflict with Flash 11.3 Protected Mode (see Adobe Forums: How do I disable Flash Player's protected mode for Firefox?)

Scanning down the front of the forums probably will yield additional suggestions: https://support.mozilla.org/en-US/questions

Please post back with your results.

Disabling Flash Protected mode fixed the problem. Thanks. But Adobe says it should only be considered a temporary solution until the real problem is found. So is there another issue or is protected mode the problem?

Mozilla and Adobe are trying to uncover the problem. Probably will be a few weeks before a final fix is available.