System Error :- Cant attach shared memory with segment id :2

Hi Team,

Once in month , we are getting system error :- Cant attach shared memory with segment id:262152 for SMAL database.There is no server for database SMAL (1423) error on all my database. 

Why this error is coming , what could be the root cause for this error.

We are solving this issue by repairing the structure file and starting the database

prostrct repair <db-name>

then 

proserve -pf "DB.pf".

is this correct way to solve this issue? if other way pls suggest.

How to avoid this error permenently

Thanks,

Vithal kattikar