could be marked as possibly-solved.
i moved the litespeed temp&swap directory to somewhere outside of /tmp and the problem has gone away.
i believed our crons watching /tmp to remove old untouched files (also aka tmpwatch) were inadvertently removing old litespeed temp files that it hadn't touched in several days. then suddenly litespeed expects the file to be there and it isnt. this also might explain why i was only seeing the error every 2-3 days.