Standby and Blue Screen

Every time we put the Dell Dimension 8300 into standby and try to reactivate, we get a blue screen.  When we cut the machine off and restart, we get a message that says "Your computer has recovered from a very serious error."  We have a Pentum 4, 2.6 GHz; /biard 0G0728; 512 ram; XP professional; Norton Systemsworks; printers, an HP Officejet 5510 and Samsung ML-2010.  We reinstalled XP with instructions from Dell and reinstalled all the software.  Same result.  Thanks for any help.  Steve