Q: My iMac has a Kernel Panic screen come up on start up and I can't get past it no matter what I try. Any help to fix this would be greatly appreciated.

Have you installed new RAM or perhaps other new hardware in your iMac?

Any external peripherals that are newly installed?

Kernel Panics usually indicate faulty,failing or incompatible hardware.

There are some fairly informative articles about kernel panics...

•OS X: About kernel panics:

http://support.apple.com/kb/TS3742?viewlocale=en_US&locale=en_US

Note the toggle triangles to get more info in the above article, some are

important steps, with alternative methods of accessing or performing a

suggested activity and may vary with the OS X version in use.

•Resolving Kernel Panics:

http://www.thexlab.com/faqs/kernelpanics.html

•Technical Note: TN2063: Understanding and Debugging Kernel Panics:

https://developer.apple.com/library/mac/technotes/tn2063/_index.html

The above TN covers several technical aspects to identify & troubleshoot.

Some are above the average user needs, but still can be rather helpful.

Hopefully you can get past the kernel panic screen, there are several

ways to attempt to do that, however if the issue is hardware, a reinstall

of the OS X may not cure the underlying cause of the symptom.

Good luck & happy computing!