1.5.4 Trashes 'Path' on install

Installation
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1.5.4 Trashes ‘Path’ on install:

My global ‘Path’ variable ONLY contains links to the fresh Panda3D install, and its Python directory - trashing all the settings I had for other software, including visual studio and openscenegraph. This is XP SP3 32bit.

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If I had it, I would give a million to the one who finds the cause of the problem.
discourse.panda3d.org/viewtopic.php?t=5032

The problem only seems to occur for some people.