[Typo3-windows] wrong path? Typo tries to write in c:/windows/system32/inetsrv/...

[Wilhelm Riphaus]

Hi Folks!
I'm having a problem with an installation on a windows server.
No images on frontend, so i told my hosting-provider to check 
permissions etc.
They told me, there could be a path problem. Typo3 tries to write 
temporary files into a system folder 
(C:\windows\system32\inetsrv\typo3temp\GB\e58cd8b31a.gif !!!), instead
of writing to the correct webaccount folder.
This temorary file is the Logoimage from "Business"-Template

Another Account on the same server runs typo without any problems.
I tried it with 3.8.0, 3.7.1 and 3.7.0 - same problem.

BTW in BE everything is O.K.
no probs with IM or GDlib - everything is fine...

IIS6, php 4.3.10

I don't know how to fix it and I also have no idea why one account is 
O.K. and the other has these problems!

Can anyone give me a clue?

Thanks in advance!
Willi