I've got a 2005 G5 Tower, got it used on eBay about 4-5 years ago and it's been a good computer but not without it's faults. However recently they have been mounting. Frequent crashes, not waking up from sleep properly and not being able to re-start without a forced shutdown most of the time. I've not have many hard crashes with the G5 but recently I've had several 'gray screen of death' where the screen goes dark and a 'you need to restart' box in the middle. Also some where a bunch of text comes down the screen but you can see what you were doing behind. Each time it has restarted without issue. Sometimes after a deep sleep the USB ports have been unresponsive upon waking up. Now I have several HDDs hooked up via a USB hub and some more network drives I access, I don't know is this is a factor and since I use them daily it's hard to disconnect them and do what I need to do as it can be days before a problems arises. I have a new iMac on the way so once I get that I can do some more testing with this. My G5 used to go weeks before a restart, but now its only a few days at most.