XP Pro not closing down & turning off PC

Recently upgraded to XP Pro with SP2. After minor hiccup getting XP to recognize some old files and old modem, a few days later ran into a problem that the PC would not shut down properly . Blue screen came up suggesting I check bios and drivers with following errors. 0x0000008E(0xC0000005 0x8062A21D 0F393FA50 0x000000000 It then dumped 100 files shut down and automatically rebooted a number of times with the same messages. Have gone into XP and cured the dumping of files but now XP does not shut down unless I push the off button after the showing of that same blue screen warning of the serious consequences of such errors. Does not seem to be a hardware problem unless my nerdy techie friend upset something inside the PC when installing another hard-drive just prior to the upgrade.