New error from (sigh) flash while using Safari

some particular site(s) ?

you've the right Flash version, not a debugger or pre-release ?

does Flash Player (Safari Internet plug-in) show up in Activity Monitor ? (Applications/Utilities) - if so, can you quit or force-quit it from there ?

Having similar problem on www.weatherunderground. Requires force quit. Newest Flash.

I am having exactly the same problem.
It happens on multiple sites (eg http://www.theage.com.au)
The error pops up and then disappears before I can click OK.
After this happens Safari won't accept any user interaction - it beeps everytime I click anywhere in any of its windows.
My confirmation test that Safari has become unusable in this way is to open the File Menu. When it has crashed, the Quit Safari item is disabled.
I do have the debugger version of Flash installed but I am using this machine to develop Flex apps so I have to have the debugger installed.
I don't have any problems with Firefox.
I am at the point now where I can't use Safari at all. Almost every site I open has some Flash in it and the slightest error will cause the problem.
It's a real pity because I like Safari over Firefox.

Chris

I did see the Flash Player (Safair Internet plug-in) in the Activity Monitor, but force quitting it did not help.

I see - sounds as if Flash has created an alert box that can't be seen, so you can't dismiss it & switch tabs or quit.
I saw in another thread that somewhitechick was also using the debugger release, so it may be the cause of this.