System slows and crashes

[eric bateman]

First off I have:
iMac G5 w/ iSight 2.1 GHz PowerPC
1.5 GB RAM
This started this morning.

It usually happens when I run iTunes and play any song; the entire screen goes blue, then the grey spinwheel spins then finder relaunches and all the programs are closed. I'm not very savy with the terminal or console but I have found a few crash reports:
coreaudiod
Exited process
loginwindow
mdimportserver

I have no idea what this means so if anyone can help it would be greatly appreciated.

My Spotlight is also constantly indexing.

[eric bateman]

Help!!!