Windows 2000 has a bug which sends applications into an infinite loop when the dialog keyboard focus (set with WM_NEXTDLGCTL) is set to an invisible control and the user hits a key. That control must be in an internal dialog which is a child and control of the main dialog. The internal control must have the WS_EX_CONTROLPARENT flag.
More information at:
little program that reproduces the problem
script that reproduce the problem
Logged In: YES
user_id=584402
Originator: YES
File Added: KillTheInstaller.nsi
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user_id=584402
Originator: YES
Original bug report by DrDan.
Fixed for 2.28.