Computer Issues

Title
I’ve just started HVE and I see a message telling me the “Application is Node Locked”. Then I see another message telling me “License file not found. Running in Demo Mode.” I have successfully used HVE on this computer before.
I am looking to buy a new computer to run my HVE software. Any recommendations?
I am seeing unexpected behaviors such as random program crashes, dialogs with parts missing or not being displayed at all, or parts of an environment model not being displayed properly in some editors. How can I correct this?
Are there any issues when installing my HVE (or HVE-2D) on a computer with the Windows Vista operating system?