Correctly applied quality thermal materials will most often last for the lifetime of the CPU and will not normally need reapplying unless the heatsink has been removed/replaced.
I am surprised that you have not had more serious problems (regular crashes and artifacting etc) than what you have presently had, your CPU has a Minimum/Maximum operating temperature thermal footprint of 5°C - 67.9°C so your computer should have automatically shutdown as soon as these temps had been exceeded, in essence your CPU is being cooked.
Has the system ever been overclocked.
Have you made any changes to the thermal shutdown temperature setting in the BIOS.
How were the temperatures that you have told us obtained.
Please provide information about your computer, this includes is it a notebook or desktop, is it a custom build or brand name such as Dell or HP, if it is a brand name provide the model name or series number (not serial) if a custom build post the brand and model name or number for the MB, Ram, add on video card if one is used and the PSU (power supply unit) providing these details will enable us to better assist you.
Download Speedfan and install it. Once it's installed, run the program and post here the information it shows. The information I want you to post is the stuff that is circled in the example picture I have attached.
If you are running on a vista machine, please go to where you installed the program and run the program as administrator.
(this is a screenshot from a vista machine)
Download then run HWMonitor and post a screenshot so that we have a comparison to the Speedfan results, details from here
To capture and post a screenshot;
Click on the ALT key + PRT SCR key..its on the top row..right hand side..now click on start...all programs...accessories...paint....left click in the white area ...press CTRL + V...click on file...click on save...save it to your desktop...name it something related to the screen your capturing... BE SURE TO SAVE IT AS A .JPG ...otherwise it may be to big to upload... then after typing in any response you have... click on browse...desktop...find the screenshot..select it and click on the upload button...then on the lower left...after it says upload successful...click on add reply like you normally would.
Screenshot instructions are provided to assist those that may read this topic but are not yet aware of the “how to”.