Hi Sue, sounds to me like a Panasonic in Bosch clothing, very common practice for them. If I am correct and I believe I am then the fault is most certainly with the inverter power supply or the magnetron or both. Prices for these parts from Bosh will be horrendous. For more help contact me direstly. My contact details are on microwave-repairs.co.uk
kindest regards
patrick, June 2009