Without Orion log, it's difficult for us to comment on the cause/resolution of the issue. If can't share it here then will suggest to open a case with support. There also we need this log.
This file should text file and should not be bigger in size.on 3/10/12 10:04:33 PM IST
You can usually find the orion.log under c:\Program Files\McAfee\ePolicy Orchestrator\Server\Logs. Just put it in a zip file and attach it to your reply (just click on Use advanced editor and you'll be able to attach a file)
Now I think your problem is being caused by this:
Caused by: java.sql.SQLException: Could not allocate space for object 'dbo.OrionSchedulerTaskLog'.'IX_OrionSchedulerTaskLog_ParentId' in database 'ePO4_S2010DSI002' because the 'PRIMARY' filegroup is full
So you don't have free enough space under your C drive or your databse might be full. If you're using SQL Express 2005 as default in ePO install then your databse max size will be 4GB. You can check this having a look at c:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\Data and looking at the ePO4_S2010DSI002.mdf and ePO4_S2010DSI002.ldf file size.