I am experiencing random shutdowns on my computer, where all of a sudden the it just cuts out to a black screen. Recent changes to the system include installation of a new 350watt Mad Dogg PSU, and a new 200GB WD hard drive in a Antec cooler unit. Case and HD temps are ranging between 95 and 103 F. System is an Asus P4B mobo with P4 1.5G CPU. Where should I start looking as to possible causes?