[mceachen]

You probably signed a clause with your employer that stated that the company owns all work/inventions/art produced on company hardware.

If you use company hardware to work on your own projects, you're muddying who now owns those projects.

When I worked on prior versions of PhotoStructure while employed by other companies, I always did so on my own time, hardware and services. I also made sure PhotoStructure was in my employment contract, specified as a "prior invention" owned only by me.