yes, need trace the root cause of litespeed restart. litespeed itself not restart often -- it must relate to the php scripts on your server.
do you have mod_security rules enabled? RC5 has big changes on support mod_security 2.5 rules. while RC4 and 4.0.20 is more compatible. it's not likely 4.1RC4 can't switch back to 4.0.20 and have to reinstall.