Remove Lib\plat-win from PYTHONPATH; that directory went away a year ago.
diff --git a/PCbuild/python20.wse b/PCbuild/python20.wse
index 1480aa6..3185395 100644
--- a/PCbuild/python20.wse
+++ b/PCbuild/python20.wse
@@ -1578,7 +1578,8 @@
 item: Edit Registry
   Total Keys=1
   Key=Software\Python\PythonCore\%PY_VERSION%\PythonPath
-  New Value=%MAINDIR%\Lib\plat-win;%MAINDIR%\Lib;%MAINDIR%\DLLs;%MAINDIR%\Lib\lib-tk
+  New Value=%MAINDIR%\Lib;%MAINDIR%\DLLs;%MAINDIR%\Lib\lib-tk
+  New Value=
   Root=2
 end
 item: Edit Registry
@@ -1614,7 +1615,8 @@
 item: Edit Registry
   Total Keys=1
   Key=Software\Python\PythonCore\%PY_VERSION%\PythonPath
-  New Value=%MAINDIR%\Lib\plat-win;%MAINDIR%\Lib;%MAINDIR%\DLLs;%MAINDIR%\Lib\lib-tk
+  New Value=%MAINDIR%\Lib;%MAINDIR%\DLLs;%MAINDIR%\Lib\lib-tk
+  New Value=
   Root=1
 end
 item: Edit Registry