electrical gremlin-any ideas?

[zimmy71]

Hi,
I have a '71 C10 with 350V8. I can let it sit for 2 or 3 weeks and it starts on the first turn of the key. I have experienced this problem twice in the last 3 months: Drive it for 10-15 miles and then park it for 30 minutes. Try to start it again and nothing-wont turn over-nothing. Have to get a jump and then it starts again. After this happened the first time I took the battery to Autozone and they tested it and said it was fully charged. There is no corrosion on the battery terminals. Any thoughts, suggestions would be greatly appreciated.