I am using windows 2000. I had a version of unity that ran and worked on this pc. a certain game repeatedly failed to load and the suggestion was uninstall unity and re download and reinstall. I did up to the point that the reinstall of the new download fails saying only runs on XP and higher. 2000 is NT tech. Is there any access to prior version?
http://unity3d.com/unity/whats-new/unity-3.4.1
This announces that Win2k support would cease at Unity 3.5.
Maybe its because you had update it to 3.5. If not tell your Unity3 Version.
- Felipe