Make sure temp partition is not full.
You should upgrade to 3.3.24 or 4.0.12, just change the version number in the download link to get it. 3.3.24 is in "3.0" folder, just change "4.0" to "3.0".
NiteWave right. I changed place where swap is stored and didn't happend again yet.
Btw there is posibilisty that check if litespeed use mmap memory? I setup it enought hight and still there are many small files in swap directory (i also incrested to max number cache small files)