Tried to install a file sharing program called Limewire. Install failed because USERENV.DLL was missing. Found and downloaded the missing DLL and tried to install Limewire again. Message box appeared to-wit;

ERROR STARTING PROGRAM
The USERENV.DLL is linked to missing export NTDLL.DLL:RtlDosPathNameToNtPathName_U


I have no idea what this means or how to get Limewire installed. Anyone have an idea as to how to correct the problem?
Thanks,