What thermo model(s) are you using? I've read here recently that the older ET-73's will freeze at a given temp if they are moved too far from the transmitter - just thinkin' out loud.
Head Groundskeeper - Squirrel Haven Estate, Lenexa, KS
Chief Cook of the infrequently competitive Fullwood Bros' BBQ Team
Cigar Lounger, Malt Beverage Tester
Owner/Operator of: Brinkmann "Lefty" Bandera clone, Comalco Black Dog grill aka The Chicken & Rib Machine, and various Weber kettles.
World's fastest Belgian/Cuban Racing Yellow thermapen.
Woody's official spousal motto: "I'm not happy 'til you're not happy!"