Restart instances automatically

 Hi,

we are using oracle 11g in linux 64 bit, but frequently our DB is re-starting itself, when I go and look into the alert log it says that

"Incremental checkpoint up to RBA [0xe.58bfe.0], current log tail at RBA [0x"

did we need to do in any parameter / setting changes.

Coz, other than that we don't have any error written on the alert log, is ther any other reliable place, where did we catch why the DB instance is automatically

re-starting.

Pls.revert me back.

Thanks,

Siva..