Even though you may have a volcano 7+ heatsink, you should check to ensure that you have it properly installed in order to optimise it's performance.
Yes, even if this means, that you have to remove the heatsink and start right over from scratch.
When you applied the TIM(Thermal interface material) did you apply it correctly to both the Heatsink and the processor, did you smooth out the paste correctly such that no gaps were present as this will cause bad heat conduction.
If you are not sure then do this again...and do it with 'arctic silver III' thermal paste...top of the range stuff.
Secondly if you feel you have done this correctly, how many case fans are you running? for an XP 2200+ i recommend you have at least one front (intake fan) and one rear (exhaust fan)...if you can afford it 2 front and 2 back...
make sure the front is blowing in and the back sucking out, else air circulation will be in conflict and can raise your temperatures. When buying your case fans Irecommend '80mm Sunon fans' they aren't flash but affordable and effective.
If you can carry out the above instructions...then you should see a significant decrease in your temperatures, and lower temperatures mean less crashes.
Finally, what type of PSU are you using, with a u'r hardware i recommend at least an antec true 380 watt power supply, the dual outake fans will also help decrease your temps.
keep us informed...
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