imac 24" G5 - Fan running constantly

Hi guys. I wondered if anyone could shed some light on this.

I downloaded Temperature Monitor 4.7 from Version Tracker on the 19th August to test my computer temperature because I was concerned it was getting a little hot but after researching a littl eon the subject I found out that it was fine and the temperature was a healthy 56 degrees C.

All temperature readings seemed fine until a few days ago. When I launch my mac, the fan comes on quite vigourously and remains on for the whole time I use it. When I check the temperature of my machine, it is stating that "Hard Drive Bay 1" is at 127 degrees centigrade??!!! This cannot be the case surely as the computer would simple melt (and it's not a hot day at all) but what I wanted to ask is if the mac is manipulated into thinking that it is actually at 127 degrees C because of the temperature monitor readings and so initiates the fan to cool down? Is this possible?

Or is it simply that my computer is knackered already??!!! (Bought it less than a year ago!)

Thanks.