Recently, I am not able to play youtube videos. I get the message "you need to install the latest version of Flash Payer" (which I have) or "you need to enable Java" (which is enabled). I installed no new programs, made no changes to settings, and tried deleting cookies & temporary internet files. I am running Windows XP Home Edition. Any ideas would be great.
I would suggest uninstalling both Flash and Java. Download ccleaner and run it for both the "cleaner" and "registry" tabs. Find this under software downloads on AfterDawn. Reinstall both Flash and Java afresh and see if this clears it up.
What web browser are you using? Make sure security settings have not changed, but I would agree with rulisky that you should consider uninstalling and reinstalling flash.