[Lis]

have you tried uinstalling/removing flash player and re-installing it?

or it could be a problem with windows...... got all the windows updates that your pc needs?

hmm the only other thing I can think of is checking the folder that your browser installs applications into, and making sure that there isn't an old version/another version installed that may be conflicting.

oh and is it possible that you have youtube listed in a virus scanner/spam filter/exclusion on your browser? your browser might be blocking the content.

wow I'm surprised I came up with all that this late at night