CPU temerature is high while CPU cores temperature is low

[bohdan.popovych.08]

I have HP-dv6 laptop with i5-460m.
Everything was OK untill the moment fans started working on full while I was just surfing web.
AIDA64 says, that CPU temp is 85deg celcium, and it does not change at all during all time.
At the same time CPU cores temps are trailing between 30-45deg, which,I think, is totally ok.
But fans are working at full and laptop is rebooting during to overheat sometimes, while air, coming out from vents is not even hot.
I reapplied thermal compound, cleaned fans, but this didn't help.
Can temp. sensor be broken?
P. S. Even when I'm entering BIOS and waiting for 5 minutes, fans start working at full
Screenshot with temperatures attached.

Spoiler

 

[CountMike]

Under CPU it's so called "package" temperature which is always higher than "Core" temp.

 

[bohdan.popovych.08]

Under CPU it's so called "package" temperature which is always higher than "Core" temp.

OK, but why then CPU temperature is ALWAYS 85, while cores temps are changing?
And why is it rebooting due to overheat even when just sitting in BIOS?
Any ideas?