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: Superior "Stealth" SS2, Brinkmann "Lefty" Bandera clone (retired), Comalco Black Dog grill, and various Weber kettles.
World's fastest Belgian/Cuban Racing Yellow thermapen.