Hi Ken,
Thank you for posting your log. Unfortunately I don't see any of the extra debugging info. Did you follow my instructions to enable it beforehand? I'm going to have to ask you to check that it's enabled and then go ahead and run through the process of trying to load an image and posting the resulting log file again (whichever is the newest one in the logfiles folder afterwards).
The 501 error is related to the graphics hardware of your system but your computer does support OpenGL 2.1, which is the minimum supported graphics version that we're targeting for PixelCNC. So you're technically in the clear but with these older versions of OpenGL (which is the underlying software layer enabling software to interface with the wide range of graphics hardware out there) things can be a little finicky, especially from a software-development standpoint. This usually manifests itself as bugs or errors and is a direct result of the OpenGL specification not being followed exactly by the implementation that is provided by the hardware vendors. Some implementations are better than others and are more forgiving toward sloppy developers while others are missing features that are supposed to be present for the version they claim to support, etc.
It's a bit of a mess, to be honest, and is unfortunately more common than you would think. It is also the reason why most new software simply does not support older graphics hardware in spite of it being capable enough. Or it just doesn't utilize it at all and instead leans entirely on the CPU alone for all of its compute work, which means slower performance. At the end of the day it's the end-users who get burned: with perfectly capable hardware they are forced to upgrade just to use newer software.
At any rate the solution will probably require making some minor changes to PixelCNC to ensure compatibility with machines running your specific graphics hardware's specific OpenGL implementation. I'd be happy to work with you figuring out what needs to be done to get you up and running. It will also benefit other potential users who would otherwise experience the same issue if they happen to have the same setup. It's going to be a little bit of a process, if you don't mind, where I will simply be sending you new test-versions of PixelCNC to test-drive and you would just report back with the logfile that it spits out. You get to do the easy part!
The first step right now is getting that debugging info into the logfile, which will provide more information and help narrow down the exact situation that needs fixing. We should be able to get you up and running pretty quick and then you'll be CNCing Xmas presents in no time! :D
^^^^ Here's the debug info option you can enable to tell PixelCNC to generate more verbosity about everything it's doing. Get that going and generate a new logfile to copy/paste here and we'll be off to the races :)
Thanks again, and happy holidays!
Charlie