This may be caused by a corrupted or missing autoexec.nt file. Here is the resolution:

1. Click on My Computer - C drive - WinNT (you may have to click Show Files) - Repair.

2. Find the file named autoexec.nt

3. Right-click and choose Copy

4. Click back (to the C:\WinNT directory)

5. Click into the System32 directory

6. Right-click on any blank space and choose Paste

7. Reboot your machine

You should now be able to complete the installation.