it happens on many different sites. I also tried to turn off java.
I reseted safari, emptied the cache, etc....
It happens after I scroll down on a site...
after a restart, it takes some time until it happens. after the first grey-out, it happens frequently...
i have to turn java off, quit safari, restart safari (with the javacripte turned off). then it seems to work.
From your Safari menu bar click Safari > Preferences then select the Extensins tab. If there are any extensions installed, turn that off, quit and relaunch Safari to test.
If it's not an extensions issue, try troubleshooting third party plug-ins.
Back to Safari > Preferences. This time select the Security tab. Deselect: Allow all other plug-ins. Quit and relaunch Safari to test.
If that made a difference, instructions for troubleshooting plugins here.