Next crash go to the XP Control Panel, Administrative Tools, and click Event Viewer. Look for any read error events. Double-Click on the event and see what info it offers, if any. Click the down arrow box to read the next until you are past the sequential read tagged errors.
Maybe something meaningful will give you a clue.
The events are last at the top and you scroll down for earlier time stamped events.
There is a free system utility that can help from MS. Go to:
http://technet.microsoft.com/en-us/sysinternals/bb545027Download Process Explorer v14.12 (May 18, 2011). Unzip the .exe into a convenient folder and create a shortcut to it. Start it up.
Right click on its status bar at the left bottom of its window. Set it up like the attached image. keep an eye on physical ram by alt-tabbing to it. If you happen to have a dual monitor setup for editing place that window there. If it looks like physical ram keeps climbing near a hundred percent. Also right click on the column header bar. Add virtual size as in the other attached file. See what process is eating up the virtual ram.