I have to reinstall Flash player on my Mac whenever I restart it, as I cannot play videos in Safari.

[Tipsy_Lurch]

This has gone on for a while now - I can't play videos on You Tube or embedded videos in Facebook on Safari - there is either a blank box, or a message comes up to say 'Plug in failure'.  this is getting very frustrating!  Please help.

[C_F_McBlob]

See: http://forums.adobe.com/thread/1267823

If that fails to resolve it, you may need to also delete the Flash Player folder from your  [User]/Library/Preferences folder

Toaccess it from Finder, hold the "Option" key and click Go>Library

Holding the "Option" key

[Tipsy_Lurch]

Thanks - I did perform the 'clean install' as well as the above suggestion and it was OK for a while, but now the same thing is happening again.  Is there a longer term solution?? 

[C_F_McBlob]

Try creating a new user account (admin) and try Safari under that account. If it works without any errors, you need to repair permissions on your account using Disk Utility.