When the phone randomly restarts itself, it is a pretty good signal that the kernel has crashed. Think of it like the blue screen from windows.
It sounds like your wife installed a program which tells the kernel to do something and the kernel handles it poorly and crashes. You can verify this by pulling the file "/data/dontpanic/last_kmsg". Usually it looks like a long, boring log. When the kernel crashes, there will be a crash dump at the end of the log that says just where it crashed. If this is the case, replacing the phone with another Elite won't fix it as long as she keeps installing that same app.
Our options for fixing situations like this are pretty poor:
1) Call LG, complain, have them give you a different model of phone.
2) Call LG, complain, provide those crash dumps and wait months for them to push an update to the Elite.
3) Find the app that is causing the kernel to crash and uninstall it and just deal with it.
4) Fix the bug yourself on your own time and void your warranty

.
Basically #3 is the fastest one that doesn't involve having to get another phone. If your wife is one of those people that just likes getting new stuff, go with #1 and let her enjoy getting a new phone.