System FAN error - but the fan is working, what to do?

I have a Sun Ultra 40 M2 running Win7 Pro 64-bit and just today it failed to boot with this error message.
I checked the obvious and all the fans are working, the main fan module with 3 fans in it and as well as the RAM fans. They are all spinning.

Any idea how to troubleshoot this? The machine displays this message then shuts down. Hitting Escape does not prevent shutdown. I have not made any configuration changes except for installing a couple of temperature apps like ControlFan but that's on the Windows 7 operating system level, this is some BIOS thing, it does not even boot up.

I have a friend that couldn't boot a HP desktop as the CPU fan was not recognized as running and it was. It was a problem on MB fan sensor. I just disabled fan monitoring on BIOS. It is working without CPU fan fail protection for years now. Not an ideal solution but the other was to replace the MB of an old computer.

In your case it seems that your BIOS is corrupted. Try to reset the BIOS (take note of its configuration).

I reset the BIOS by removing the battery for 15 minutes. That did the trick. It boots up just fine now.

I installed several temperature polling apps and they screwed up the BIOS royally, at least one of them did.

I will never install these temperature apps ever again. It was a scary moment for sure. I thought I bricked something in the BIOS/motherboard. This is an old AMD motherboard, Oracle bought Sun and course they no longer support BIOS upgrades. And when they did, it was a moot point as you had to have a support contract in place. Not cost-effective for this 10 year old piece of junk.

Mental note: Don't install random stuff off the internet.

Open hardware monitor is a free application that doesn't need to be installed. Downloads - Open Hardware Monitor
Extract files to folder C:\Program Files (x86)\HardwareMonitor, execute the OpenHardwareMonitor.exe
It only reads the sensors. It has an option to start with windows.