Computer freezes with display replacement [updated]

Original issue: We recently replaced the display on this MacBook. After installing the replacement, when we screw the bottom casing back on and use the computer, the entire system freezes (display stays on, nothing moves, won’t go to sleep).

However, if we leave the two screws in the top corners of the bottom casing out of the machine, it works perfectly. Also, it works perfectly in safe mode regardless of whether the two screws are installed or not.

The screws in the corners are the correct length. An SMC reset and NVRAM reset didn’t affect anything. I can’t for the life of me understand why those two screws would have anything to do with it, is it just coincidental or is something going on?

Update: So perhaps the screws were just coincidental. We just booted it up with the bottom casing on but not screwed in, and it still froze after around a minute. We are going to reinstall the operating system and see if that helps at all. Intermittent problems are the worst :)

Update 2: Disabling login items and reinstalling the OS (on top of the existing install) didn’t help. If we don’t boot in safe mode it freezes a minute or so after boot regardless of whether we login or not anyways.

Update 3: We put the old display back in the machine and it no longer freezes at all. So I don’t really understand this issue. What would cause a MacBook to freeze randomly with a replacement LCD (Apple OEM part of course), but not in safe mode? And somewhat intermittently?