Hi Katy,
Have you checked the drive for possible errors using Disk Utility from your system restore disk(s)??? Even though you've erased the drive, try it anyway. If DU reports errors, click Repair. Here's how to do this just in case:
Now, grab your system restore disk. Make sure your Mac is turned off. While holding the C key, press the power button and insert the restore disk all at the same time. The Apple logo will appear on the desktop... at that point, let go of the C key. Now, an installer screen will open. Quit the Installer from the Menu, and click Utilities/Disk Utility from the Menu. Now when DU opens, select MacintoshHD in the panel on the left. Then with the First Aid button selected, click Verify. If DU reports errors, click Repair. If there are errors, hopefully DU can fix it. When it's finished, Quit Disk Utility from the Menu and then click Utilities again, then click Startup Manager. When that window opens, select MacintoshHD 10.4.10 and click Restart.
And something that just dawned on me. How much available drive space do you have? To view this info, open any Finder window. Available drive space will be at the bottom. Never allow your Mac to fall below 15%. It takes that much to just boot.
Also, I know you've reinstalled all your graphics software, but if you have to do this again, just install one. See if it crashes. Then install another one... and so on. One of them is causing this... I just best cha!!
Carolyn 🙂