[lizardgator]

I have a 1.8 Ghz G5 iMac with 512mb of memory. OS X seemed to be dragging so I ordered an additional 512mb of ram from Crucial and received it today.
I installed the ram, rebooted and after the gray Apple boot screen appeared as usual the OS X boot screen came up and just petered out after a second, the revolving circle would reappear and disappear at random finally ending up with a blank blue display.
Thinking that either the new ram was either defective or not seated correctly I both removed it and reseated it but every time I rebooted the same thing happened. At this point not being a happy camper the final straw was to try and reinstall OS X. I did, it went without a hitch and now everything is working fine again, the new ram shows up and is working fine.
So this begs the question, what could have happened to cause OS X to crash the way it did. Since the ram is functioning normally I’m at a loss to explain what the problem was. I’ve installed ram many times and never had a problem like this.

[Gossamer]

Did you try running Disk Utility on your startup disk before reinstalling? That could have saved you a lot of trouble and maybe even told you what the problem was.