Hi stan, is this a G5 maybe?
If you don't know the model, find the Serial# & use it on one of these sites, but don't post the Serial# here...
How to find the serial number of your Apple hardware product...
If you hold alt key at bootup, do you get a screen shoeing boot choices?
Kernel panics are usually caused by a hardware problem – frequently RAM, a USB device or a Firewire device. What external devices do you have connected? When trying to troubleshoot problems, disconnect all external devices except your monitor, keyboard and mouse. Do you experience the same problems?
Do you have an Apple Hardware Test disc (the AHT is on the Install/Restore DVD that came with your Mac)? Running the Apple Hardware Test in Loop Mode is an excellent troubleshooting step for finding intermittent hardware problems. It is especially useful when troubleshooting intermittent kernel panics. If Loop Mode is supported by the version of the Apple Hardware Test you are using, you run the Extended Test in Loop Mode by pressing Control-L before starting the test. Looping On should appear in the right window. Then click the Extended Test button.The test will run continuously until a problem is found. If a problem is found, the test will cease to loop, indicating the problem it found. If the test fails, be sure to write down the exact message associated with the failure.In some cases, RAM problems did not show up until nearly 40 loops, so give it a good run.
May be a solution on one of these links.
http://docs.info.apple.com/article.html?artnum=106227 What's a "kernel panic"? (Mac OS X)
http://www.macmaps.com/kernelpanic.html Mac OS X Kernel Panic FAQ
http://www.index-site.com/kernelpanic.html Mac OS X Kernel Panic FAQ
http://www.thexlab.com/faqs/kernelpanics.html Resolving Kernel Panics
http://www.macfixit.com/article.php?story=20060911080447777 Avoiding and eliminating Kernel panics
http://macosg.com/group/viewtopic.php?t=800 12-Step Program to Isolate Freezes and/or Kernel Panics