Default Phone lost settings & device id???

I've been running Phoenix ROM v7.3 on my I9505 for a few months now. In the last couple of days it's started acting strangely...yesterday the home button stopped responding (it would turn on the screen, but nothing else). I tried rebooting a couple of times but it didn't help.I also noticed that some of my sound settings had changed without any intervention from me - phone ringtone, notification sounds, sounds when touching the screen. This morning I ran Titanium Backup and it told me that my device id had changed, and asked if I wanted to restore my previous id (which is what it did when I first flashed the ROM a few months ago). I answered "yes" to this, and let the phone reboot, and now my home button seems to be working again.

I know the obvious thing to do is wipe and reflash, but does anyone know why this sort of thing happens?