A little progress: there is a section on IBM's BIOS update page that explains how the BIOS might need to be initialized after an update. I'll borrow from their page:
Initializing the BIOS
BIOS Initialization is suggested for some problems. To initialize the BIOS settings:
1. Turn off the system.
2. Turn on the system.
3. While the To interrupt normal startup, press the blue ThinkVantage button message is displayed at the lower-left area of the screen, press the F1 key.
4. The BIOS Setup Utility menu will be displayed. If you have set a supervisor password, the BIOS Setup Utility menu appears after you enter the password.
5. Press the F9 key to load default configuration.
6. Select Yes.
7. Press the F10 key to save default configuration and exit.
8. Select Yes.
Notes:
After initialization you may need to reapply some settings that you had changed previously.
After the initialization has been completed, the system restarts automatically.
The link to this article is
http://www-307.ibm.com/pc/support/site. ... 63024.html
This allowed me to use my LCD as the primary monitor now, but I still have the Code 12 error. The bottom of the above mentioned article has previous BIOS versions on it, so I am going to try and revert to 2.17 and see if that helps.