My friend is having this issue on his iMac running 10.7.5. YouTube videos hang up or won't play in Safari. What we've done (previous fixes on other threads) *flash is up to date *removed all website data *checked HTML5 trial -not enrolled *Looked for nc-pcc-dir-shockwave plug in - not there *changed Safari to 32 bit mode *Installed clicktoflash extension - no change Maybe we didn't quit/relaunch safari after performing a step. I honestly can't remember. But the computer has been shut down and powered on since we tried everything with no change. We tried Chrome which had the same issue. He didn't want to try Firefox but maybe I can change his mind. Everything did work correctly in a brand new user. Thoughts on next steps? I appreciate the help.