iphone slider & touchscreen won't work ... but only after using one app

[lurkingfromhome]

Oh this is weird. I have a running app on my iphone (with GPS). The last three times I've gone out for a run, the run comes to an end, I close the app and then the touchscreen stops working on my iphone, so I can't slide to unlock. No amount of rebooting makes any difference. The first twice this happened I had to do a restore from itunes.

I thought it might be a bug in the app, so I deleted the app altogether and installed another similar one instead. When I wasn't using the app, the phone worked perfectly. Went out for a run this morning and it's happened again. The run finished and before I even closed the app everything froze. I can't slide my phone open and so can't use it.

Any thoughts? What can this be? Is it something to do with the GPS?

Where are you storing phone while running ?
Maybe it's getting too hot stuffed in your bra pocket ?

You know, I never thought of that. It's stored in a little inside pocket of my jogging pants, at my waist. yesterday it didn't work for three hours or so after my run and then mysteriously sprang into life. I wonder if it is overheating. Thanks, worley, I'm off to google "overheating iphones" and see if it could be that.