Delphi 2007 - Error compiling in Vista32

Hi
When logged into Windows Vista as Administrator everything works fine
Wen logged in as 'normal' User with Administrator rights D2007 seems not to
find the pathes to its own components unless I define the Path in each and
every project.
Error Message (translated):
F1027 Unit not found: 'System.pas' or binary equivalent (.dcu)
Setup.exe(1): the required process requires elevated rights

Does anyone have a workaround?

Thanks
Martin Sommerhalder