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The root cause it that Purify renames all DLLs with names like
"python24__d$Purify_c_python.dll".
With python 2.3, this name was not taken as the python DLL,
and no check was performed.
The broken logic in my previous comment changed this for 2.4.

A more correct fix is to get the python DLL name from the
current process, using GetModuleName(PyWin_DLLhModule).