When you install memory in most Mac systems, provided everything went well, the computer will simply boot with a new memory capacity. However, on the Mac Pro you might see a tool called Apple Memory Utility launch to indicate a new memory configuration has been detected.
This tool should show only once and state whether or not the installed memory is in the recommended slot configuration for optimal performance. In some cases, however, this tool may load every time you boot the system after upgrading. While it can be dismissed by pressing the OK button, having it load each time the system starts can be a bit annoying.
After experiencing this issue with his Mac Pro system, MacFixIt reader Warren found that the problem was rooted in his standard administrative account's inability to write an appropriate dismissal of the message to the program's configuration and thereby prevent it from displaying all the time. However, even if a problem prevents a standard admin account from proper access to administrative tasks, the system's root account ought to be able to access it. So, by enabling and logging in once with this account, Warren was able to trigger the system to dismiss the persistent message.
To enable the root user in OS X, go to the Users & Groups system preferences. Select the Log-in Options below the user list, then authenticate and click the "Edit" button next to the "Network Account Server" status. Next, click the button to open the Directory Utility. After entering this utility, again click the lock to authenticate, then choose Enable Root User from the Edit menu. You will be asked to provide a password for the root account, after which you can log out and then log back in as the root account.
When logged in as root, keep in mind that there are no restrictions to any system resources so you can potentially harm the system without any indication. With this in mind, it should be used only to log in and perform a specific task, and then be disabled. For the purposes of this situation, log in to the root account and click the OK button for the Memory Slot Utility when it pops up. Then log out and log back in to your standard administrative account, and immediately disable the root account using the same procedure in Directory Utility described above.
This problem is related to an earlier one where users were seeing a similar message appear at startup from the Apple Memory Slot Utility. However, rather than having legible text, it was showing garbled messages that appeared to be the underlying code for the text and buttons of the message window. At the time this issue was resolved by removing the memory slot utility. While this is still one option, it may also be addressable by likewise logging in as the root user and disabling the root account.