My automatic test-framework tests a bunch of Excel sheets required by our customers with the excel plugins that my team provides. In order to test the sheet I need to call some macros, this in turn requires macro security to be set to lowest on the testing servers. (In production macro security will be on). In particular I need to supress this dialog:

One particular PC seems to resist my attempts to configure it, having set macro security to low from Tools->Macro->Secyrity… I exit Excel and return to it, only to find out that macro security has been reverted to ‘medium’
I’m guessing that I’ve inherited a PC which has a registry setting that prevents me from downgrading the security, I’ve searched around and found ‘[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\11.0\Excel\Security]’, however this does not seem to do the trick.
I wonder if there is another way to force macro security to it’s lowest setting, either programmatically (via COM) or through a simple registry edit.
UPDATE: I’m on Office 2003. My PCs were pre-owned by other users and may have all kinds of configuration inconsistencies. Of all the PC’s under my care this issue only affects one machine. I have full admin rights.
HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Excel\Security\VBAWarnings=1 (REG_DWORD) is the setting you’re looking for. It can also exist under HKLM as a machine-wide override. The location also varies by office version; 2003=11.0; 2007=12.0.
Lastly, if you are in a managed IT environment, keep in mind that group policy may be changing it back for you.