I get a message "The UDF driver is not installed properly" under Windows XP, when I start up Windows, and InstantBurn 5 will not launch.

The InstantBurn 5 compatibility mode setting may be unsuitable under Windows XP. Use the following method to check it. 

1. Right click on the InstantBurn shortcut on the Desktop or in the Start menu. 
2. Select "Properties" from the menu. 
3. Click on the "Compatibility" tab. 
4. Check if "Run this program in compatibility mode for" is enabled (checked) under "Compatibility mode". If so, you can select a suitable OS from the pull-down menu located below "Run this program in compatibility mode for".