AutoCAD 2009 & 2010 users – out of memory errors?

Some of the users I support have repeated out-of-memory errors while editing fairly simple drawings. I have some 2010 users who suffer from this problem while others using the same drawings on the same hardware get by without ever seeing it. When swapping users to differerent PCs, the problem seems to follow the user. Despite various experiments, I have no idea what is going on here. Is this happening to you or anybody you work with? Have you managed to work out if there is something that triggers it? Is there a user interface setting or method of drawing that …