db is getting down frequently on linux

Hi
 we have database having version 11.2.0.2.0 on linux platform. After starting the database, it is getting down immediately. It is not giving any error in alert.log file, but one trace file getting generated with the following error

body { margin: 0 0 0 0; padding:0 0 0 0 } td,div { font-family:Tahoma;font-size:8pt;vertical-align:top } /* Copyright IBM Corp. 2011 All Rights Reserved. */ body { margin: 0 0 0 0; padding:0 0 0 0; overflow:hidden; } .transcript { background-color:#d2d2d2; } .messageBlock { padding-left:10px; padding-right:10px; margin-bottom:3px } .message { padding-left:20px; margin-left:95px; word-wrap:break-word; white-space:-moz-pre-wrap; _white-space:pre; white-space:pre-wrap;} .messageCont { padding-left:20px; margin-left:95px; word-wrap:break-word; white-space:-moz-pre-wrap; _white-space:pre;white-space:pre-wrap;} .other { font-size:11px;color:#39577a;vertical-align:top;font-weight:bold;font-style:normal;float:left; width:95px; } .myself { font-size:11px;color:#da8103;font-style:normal;font-weight:bold;font-style:normal;float:left; width:95px; } .otherCont { font-size:8px;text-align:right; color:#39577a;font-family:Arial,Lucida Grande;font-style:normal;vertical-align:top;font-weight:bold;float:left; width:95px; } .myselfCont { font-size:8px;text-align:right; color:#da8103;font-family:Arial,Lucida Grande;font-style:normal;vertical-align:top;font-weight:bold;float:left; width:95px; } .system { font-size:11px; word-wrap:break-word;color:#da8103;font-style:normal;font-weight:normal; white-space:-moz-pre-wrap;