Could possibly be a stability issue with fwm or cpm processes, what does cpwd_admin list say?
What are the specs of the SMS hardware?
Also check the health of your RAID setup (if applicable), and the underlying hard disks via /var/log/messages*. Also any hardware issues being noted by cpstat -f sensors os? Failing hardware can cause some strange effects that are hard to pin down.
Attend my online "Be your Own TAC: Part Deux" CheckMates event
March 27th with sessions for both the EMEA and Americas time zones