Everytime I execute the startup command the following logs are generated ----
(1) [ OCROSD]utopen:6':failed in stat OCR file/disk /oracle/oragrid/product/db10g/
cdata/localhost/local.ocr, errno=2, os err string=No such file or directory
(2) [ OCROSD]utopen:7:failed to open OCR file/disk /oracle/oragrid/product/db10g/cdata/localhost/local.ocr , errno=2, os err string=No such file or directory
(3) [ OCRRAW]proprinit: Could not open raw device
(4) [ default]a_init:7!: Backend init unsuccessful : 
(5): [ CSSCLNT]clsssinit: Unable to access OCR device in OCR init.
---- any idea about cause /resolve
when large volume of data inserted/retrieved to the database, instance will not work properly and needs to be restarted. I am using Oracle 10g Enterprise Edition
Seems to be your cluster services and asm not started,
The order is, first crs should be started, then asm should be mounted and started and then nodeapps(listeners, vip, etc) should be started and finally database should be started.
So try to find out where your problem starts and let us know..