Do a restart, restart fixes alot of problems(if you use windows as your main OS) by reloading all of the kernel. That should fix those software tempgauges aswell.
This problem happens to my old almost 9 year-old laptop. Whilst having windows 7 installed it stopped the fan from spinning and tempgauges were locked when my computer went to sleep or hibernate(everything works with cold boot and restart).
Gets worse with windows 8, by skipping some steps in driver relaoding in kernel, the boot speed is amazing(like 7-10 secs with an old 120gb 7200rpm hdd), but the drawback is obvious, the fan stops, tempgauges aswell. It's not overheating or anything, just running hotter than usual. Plus the added bonus of a silent computer is awesome