Internet Explorer 6.0 will not start.

I have a users whos OS is XP and running Internet explorer 6.0. The problem I am having is that his internet has stopped working all of a sudden. The message I am receiving is having trouble with iexplorer.exe and the WINDLL.DLL and the NTDLL.DLL files. I have tired to remove internet explorer using the remove programs from the control panel, and downloaded from MS the internet explorer 6.0 with sp1, and still am getting the same errors concerning these two file. I have tried to copy these files from another XP machine and that did not work, same error. Can you help?