Three of them are behaving perfectly. The fourth is behaving oddly. Every account occasionally brings up the prompt 'Windows needs your permission to continue' when performing admin functions - e.g. viewing/copying folders from other accounts. On the three 'normal' accounts choosing 'continue' either works straight away, or brings up just one more prompt before doing so. The badly behaved account accepts the command, but then does nothing. I have checked in the control panel, and it says it is an Administrator account. I have tried changing the account status from another account, only to be told it's already an Administrator. I understand that 'UAC' sometimes has something to do with this, but since I have no idea where that is or what it is and I'm the only person who messes with this machine, it must be at the same setting as the other three accounts. Also, until yesterday there were only two 'admin' accounts (plus the 'hidden' one I'd no idea about) of which the naughty one had been set up for some time. Two of the well-behaved accounts were only set up yesterday. I set them up because the naughty one wasn't behaving and I needed a clean admin account.
Any ideas what's wrong?