Somehow I seem to have gotten PHP to dump core, haven't I?

Not necessarily - whats in the error log?

I did some research, and what I made happen with a certain infinite loop was PHP to crash. Apparently it crashes in such a way that it dumps all current state and variable data into those core.nnnn files. I somehow managed to do it in a loop that pushed elements onto an array; it seems I accidentally made it an infinite loop, but it should have just come up with a Max Execution Time error. I guess PHP isn't bugfree then. Just for reference:
http://www.zend.com/tips/tips.php?id=170&single=1

The fact that you can get it to crash accidentally is a pretty bad sign...

Um... what other ways are there of causing things to crash? Its always accidentally

@Kerm: You might ask your host to update your PHP version, although I doubt they will

Agreed, and I have no idea precisely what I did. I can only imagine that PHP segfaulted on me.
@Kllrnohj: yeah, I doubt it as well, but I suppose it's worth a try. Keep in mind that every new version introduces its own new set of bugs.