Temps in the 40's and mid 50's are fine for AMD's, They can usually take up to 65C pretty easily, but I personally dont like it up there. My 2400+ XP would be at 64C idle and it was like that for months. It probably was just your ram giving you troubles. When you get the new ram try some memory diagnostics. Your temps that you posted dont seem high enough to cause the system to shut down unless you have its shut down temperature at that temp