Error 57 when adding item to validation list

Symptoms: A error message similar to the message below occurs after attempting to add an item to validation list:

The path listed on line 2 for "LST.$" is a temporary work file in the ARM work path listed on File tab of Tools - Options dialog, and is different for each ARM session.

The path listed on line 4 identifies the validation list to which you are trying to add a new item.

Cause: Your Windows user account does not have permission to overwrite files in the ARM study definition folder that is listed in line 4 of the error message.

Solution 1: Start ARM as an Administrator by changing properties of the ARM desktop shortcut as below:

A. Use mouse to highlight ARM 8 icon on Windows desktop, then click right mouse button to display context menu:

B. Click on Properties with left mouse button, then select Advanced button on Shortcut tab and check "Run as administrator":

C. Click OK buttons to close dialogs. If prompted to reboot computer to apply this change, then reboot before starting ARM.

If this does not solve the issue, then try solution 2.

Solution 2: Contact your IT administrator, and request changed permissions so you are allowed to create and modify files in the ARM root study definition folder (C:\ProgramData\ARMdef in the example above). See the required user rights and permissions document for details.
Your IT department can also assist with storing ARM studies on network drives that require administrator rights.