I purchased a preassembled hacker shied with an icsp header attached so that I could use it with both the arduino uno and the arduino mega board that I have.
What I have found, however, is that I cannot seem to power my mega board directly from a 5v supply across Vin and Gnd with the shield attached as I could otherwise do without the shield. I have had no problems using it with the Uno like this.
The shield does,apparently, otherwise function correctly.
I am not sure what happened. It appears to be working normally now. I do not know what I am doing differently. I was going to see if it worked across the +5v and gnd lines, but it seems to be working across Vin and Gnd now just fine.
Please ignore this question. I must have had it plugged in wrong.