I think you have another UxTheme.pas or UxTheme.dcu in your search path or a compiled
package. You could try to delete all but the standard entries
Code:
$(
BDS)\lib;$(BDSUSERDIR)\Imports;$(
BDS)\Imports;$(
BDS)\Lib\Indy10;$(BDSCOMMONDIR)\Dcp;$(
BDS)\include;$(
BDS)\RaveReports\Lib
from your search path.
If this doesn't help try a repair installation of your Delphi installation.