what does "Warning: SUID file “System/Library/CoreServices/RemoteManagement/ARDAgent.app/Contents/MacOS/ARDAgent” has been modified and will not be repaired.

That is not from ( Repair Disk ) it is from ( Repair Permissions ). If your disk is slow, be certain you really did ( Repair Disk ).

Repair permissions is only needed when Applications are not launching properly. Most of its messages are warning that items have been updated, and their permissions are not the same as when installed.

Apple Remote Desktop (ARD) Agent is used in large corporate environments to check software versions installed on flocks of computers from a central Admin computer. You are not likely to be using it, and if it is having problems, your sytem administrator will see that and will be at your computer to fix it in a day or two.

Displays menu is the little display Icon that can be made to appear in the MenuBar to show you the last three resolutions you set. You may not even be using it. Don't worry about these.

The last couple of days -- several times -- my MacBook Pro running Mountain Lion wouldn't start. I had to force quit and then start the computer again. Also, I am no longer able to access files on my employer's website via vpn since then though I can from a different (older) iMac. I got the same Warning SUID file message. How can I repair disk when I have no 'original DVD'?

Your problem is with a notebook, not a workstation.

MacBook Pro
https://discussions.apple.com/community/notebooks/macbook_pro

jotex-

The original poster's complaint, SUID messages, is almost never the cause of the problems he has described.

It also cannot possibly to be the cause of YOUR problems.

Please start a new thread, with a catchy title, in the approriate forum area for MacBooks, and Readers can begin to respond to your actual symptoms.