Basically, the way the MDW security has been implemented in MS Access is piss-poor.
When I had a similar problem (nowhere near as many as 4,000PCs just lazy really) I set up a Reg file which is more easily applied.
The contents were :-
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\8.0\A ccess\Jet\3.5\Engines]
"SystemDB"="G:\\Database\\STPSecurity.Mdw"
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\9.0\A ccess\Jet\4.0\Engines]
"SystemDB"="G:\\Database\\STPSecurity.Mdw"
which, you'll notice covers two versions - 2K & 97.
The file was created using RegEdit.Exe (all the usual warnings etc.), after I'd set up my PC with the correct settings.
From the 'Registry' menu select 'Export Registry File...' making sure 'Export Range' is set to 'Selected Branch'.
Obviously, the key used for later versions of Access is likely to be different, but only in the version number bits I would guess.
To apply the Reg file, simply Open it from Windows Explorer or type it in the 'Run' box.