Metro 2033 and PhysX

Hi all, I'm having problems with this game I bought on steam and THQ have been very unhelpful. I've posted my original email to them below. Any help appreciated.

Original email:

Hi I'm having a few problems running the Steam
version of Metro 2033. The first I believe is quite
common, where a message appears saying
"PhysXloader.dll is missing from your computer." I
have tried the recommended solutions for this of
restarting steam, and also my system.

This gets rid of the message however when the game
opens, nothing at all happens and I am left with just
a black screen. I am then unable to leave the game
through ctrl+alt+del, and the only solution is to
restart the computer. I am then unable to boot into
windows, and I have to do a system restore though
safe mode, restarting to a point before physX was
installed.

The problem seems to be physX and I am unsure where
to go from here. Thanks for your help.

Response from THQ:

Thank you, Jamie, for contacting THQ Customer Support.

PhysX is a thrid part program developed by Nvidia and it should not cause any of these issues. The lack of being able to get back into Windows would tell me there is a deaper issue causing these problems to appear.