Sperando che sia gradito faccio un "paste" della parte che mi interessa.
Disable Cancel button on Logon box (Win95/98)
If your Win95/98 Computer is used in a multiple user environt (see above) you can restrict the computer useage for just authorized users by disabling the Cancel button in the Login box. Follow these steps:
Go to the Start button=>Run, type in regedit and press OK.
Locate the directory HKEY_LOCAL_MACHINE\Network\Logon. If the Logon directory is missing, create it by right-clicking on the Network folder, select New=>Key and type in Logon
Right-click in the right window pane and select New=>DWORD Value and name it MustBeValidated . Make the value 1 (one).
Exit the Registry Editor and restart your computer.
The Cancel button is now disabled. To re-enable the Cancel button delete the MustBeValidated name in that you created in step 3.