I've been having this problem with my car since the summer, I used to think it was heatsoak because it was so hot outside and very hot under the hood (specially under the manifold) that the starter got hot enough that it wouldn't crank.
But it was like -5C yesterday and the damn thing wouldn't crank! this was after I drove home from work and tried to restart the car 15 minutes after I had shut it off. Sure I was on the highway for about 1 hour, but I didn't think it would be an issue in the winter since the air coming thru the front would be really cold and it would keep the temps a little even.
I had to roll-start my car backwards (thank God for steep driveways!

) to go and stay over at my girlfriend's place, I seriously thought my starter might be gone this time but guess what! I turn the key this morning and the starter cranked!! I'm not sure now if the starter needs replacement anymore but who knows could be something else.
Any other ideas as to what's causing this problem other than heatsoak on the starter?? maybe its something I'm missing, like a relay or even the switch for the clutch. Remember we have to push the clutch in to start the car, I'm not sure where exactly this switch is located (hopefully someone knows) I'd like to know how to bypass it to see if this might be the problem.
Any help would be appreciatted, and Itchy.. hope you still got that starter for me, and maybe even an alternator.. I'd like to have rebuilt extras of both in case I might need them. Thanks in advance guys!