The PMDG 737-800/900 was working fine, until I install the SP1 for the 737 and installed the expansion, after i installed these, the game loaded until the main menu, then Fatal Error. I've tried to uninstall the expansion and repair, but it just got worse, the crashes before the main menu appears now.

http://support.precisionmanuals.com/Main/Default.aspx

Did you install SP1C for both the base and expansion?

 

https://www.precisionmanuals.com/pages/downloads/updates.html