Not sure if this has been mentioned before but thought I'd post it anyway

Symptom;
When using IE8, Windows Update site crashes with a "Instruction at 0x07f**** referenced memory at 0x07f****" message when checking for ActiveX controls, after installing XP SP3 and/or IE8

Fix;
Go to IE8/Tools/Internet Options/Advanced/Security & Uncheck Enable memory protection to help mitigate online attacks.