ok so first if your running it on anything other than the intel lga 1366 mobo thats going to have a affect and did you remove the old pasteif not try that and by the way the stock coolers suck ive had probs with them on a core 2 duo man and they run cool!
There must be something wrong somewhere as Intel isn't going to ship a fan/heatsink that is just going to lead to complaints, makes no sense.
You've also confused me with degrees C and degrees F, which is it?
If the figures are fahrenhiet which equals a range of 41C to 57C that sounds absolutely fine to me and well below maximums so maybe there is another issue somewhere with it shutting down, something else may be overheating. Is the power supply adequate and working correctly?
Hope you sort it out.