Several Xcelsius users who have tried to use add-on components have reported that Xcelsius crashes when accessing the add-on manager. As it turns out, it is Windows Vista's User Account Control that causes the crash. UAC is the first feature I naturally turn off when ever I image a new machine with Vista so I had never experienced this issue. In turning off UAC, you allow Xcelsius to execute and install add-ins.

Here are the steps to disable this Vista feature:

1. Launch MSCONFIG by from the Run menu.
2. Click on the Tools tab. Scroll down till you find "Disable UAC". Click on that line.
3. Press the Launch button.
4. A CMD window will open. When the command is done, you can close the window.
5. Close MSCONFIG. You need to reboot the computer for changes to apply.
6. Next time you open Xcelsius, you can install your add-ins.

If you are running 64 bit windows operating systems, the Add-on manager crash is a logged bug with BOBJ and hopefully will be fixed in the next Xcelsius release.