Windows 7: How to diagnose reason for mystery startup error message?

At my new job I've been using Windows 7 for only a month (XP at home). It's run very smoothly until I got back from the new year's weekend. This morning a DOS-style screen came up with two startup options. One said something like "attempt startup repair (recommended)" I wasn't taking notes because my boss was looking over my shoulder. I went with the recommended choice came to a big dialog box saying something like "system was unable to start normally, click here to attempt repair." After less than 10 minutes it was up and running.



I've spent all my time here learning their internal software systems. I haven't had time to learn all the performance tweaks and system integrity checks I know about my XP at home. Any tips on how I can diagnose what happened this morning? Heck, even a link to a known reliable page on 10 best practices for keeping Windows 7 healthy.
(Looked at your "Crash and lockup debug 'How To'" but didn't see anything applicable to what happened this morning.)

Found some more info about this at MS as "Kernel Power Event 41" that said diagnosis was usually looking at what the computer was doing before the error. However, the Event Viewer only shows three normal startup steps before the critical error.