I'd check your battery fluid levels first, make sure it's nicely topped up.
Also, is it a Banner Battery? (one of the old starting bulls), since I had issues with my old one.
I had the exact same problem you describe, pulled onto petrol forecourt after quick blast down the road from my house, went to restart and sounded like a dead battery.
After a cool down period, she started again no problem so it was as if the battery was over heating.
I understand K-Series engines can have starter issues, but I replaced my very old and leaking 😳 banner battery with the powervamp and she has no more starting problems whatsoever.
Edit to add - I moved my battery earth point (negative lead) to a different position on the engine, with a cleaner join thanks to some emery cloth and some good ol' vaseline, may have improved matters too.
Edited by - TeKK on 25 Nov 2009 16:37:30