Try this:
Reboot the Computer
Run ScanDisk and check for errors
Bioware mentions the following in their tech help forum concerning a similar installation bug:
Reinstallation Bug Fix:
1. Download a program called RegCleaner from
www.majorgeeks.com)
2. Run this and remove any traces of "KotOR", "LucasArts" and "BioWare".
3. Open up "My Computer" and select "Tools" at the top toolbar. Then select "Folder Options". After this go to the "View" Tab and select "Show hidden files and folders".
4. Go to C:\Documents and Settings\[user name]\Local Settings\Temp. Remove all files in this folder.
5. Now go to C:\Program Files\InstallShield Installation Information. In here delete the folder with the following title: .
One suggestion: always backup your registry before cleaning anything in case you mess out.