I often see negative figures with speedfan as well and I'm not convinced this is a hardware problem, more likely a software problem.
I am using the hardware monitor from cpuid.com now (http://www.cpuid.com/softwares/hwmonitor.html) and don't see those negatives anymore.
That being said, you do have a serious cooling problem and at those temperatures, you risk damaging your hardware. If a standard fan doesn't provide the necessary cooling in your environment, you may want to consider liquid cooling. These days, there are decent models at the price of a high-rated fan (e.g. Corsair Liquid Coolers). I have bought an entry level for my i7 and under medium load (while gaming), my cpu doesn't go over 40C. Constant load under prime95 is about the only thing that can push it towards the 60C.