My dad's iMac G5, 2.1 GHZ, 1.5GB RAM, 500 GB HD, 10.4.11 is having problems. It has gotten incredibly slow, and freezes about every 2 hours. I first ran Onyx to see if anything is wrong and I did a quick disk repair and cleaned out all the unused files, etc., I than checked how much hard drive space it had, and it seems fine, 333 GB left. This iMac had similar problems about 2 days ago, before we even ran the updates. Any ideas?