Hi my Hitachi tv also does the same. Appears to be a common fault of this make. My tv is only 4 years old! I got a repair guy to give me an estimate to repair it for GBP 70 cash, next day repair. He told me that the regulators should last for years but reckoned a probable cause for the fault was that we left the tv on standby too much. I don't know for sure but... will see how the repair goes!
SC
January 2007