Win32 / Emacs 21.3: Crash when any of customize-* function is used

[Andrzej Sołtysik]

With precompiled 21.3 Win32 binaries, totally reproducible crash occurs when
using any customize function. Tested on Win95, NT 4, 98, and W2K, each time
the problem is exactly the same:
After invoking any customize* function, Fatal Error dialog is shown, with
Abort/Retry/Ignore choices. Each of them ends in emacs termination, although
Ignore causes "This program performed illegal operation" dialog to be shown,
with crash in module <unknown> and bogus address like 0000:00000007
suggesting null pointer reference. Last message shown is "Loading
wid-browse... done". This crash occurs regardless of wether any .el files
are loaded; with -q, --no-init-file, --no-site-lisp results are the same.
Tarballs grabbed were -fullbin ones.