automatic time log off - mozilla users also

my members told me that they have been logged off by time...
for example they are writing longer post, and when they want to send it. they need to log in again and than they lost all written.

is there a way for this automatic log off to be prolonged or turned off???
thanx

Why am I guessing they use Internet Explorer?

THIS might help them if they are.

hehe... This is my first thought too
Ill see. thanx

but what Mozilla users can do???
plz