Just a thought, if it doesn't happen at home or in a hot garage could it have anything to do with the power supply at your Thursday night show ?
Perhaps you could try a power smoothing device.
Another thought is, if your computer has wireless enabled turn that off as perhaps it is picking up some interference at that bar.
Do you have any extra things plugged in to your usb outputs for your Thursday night show ? as these all drag power from your computer.
I know these are long shot ideas but we seem to be running out of suggestions.
Roy.