I do hope that you are not running the thing empty. For most domestic microwave ovens running empty is serious abuse. Beyond damaging the machine, worst case, you could start a fire... http://www.repairclinic.com/0088_6_2.asp http://www.fda.gov/consumer/updates/microwave112107.html Unless you have specifically checked your manual for a statement that it is safe to operate empty - don't do it, please! Its cheaper and safer to use a simple purpose-built timer. ← LOL. What portion of microwaves don't have separate, designated "Timer" functions? 5%?