What is the exact problem you are facing in your SEPM?

Are you able to find any related entry in event viewer?
like unexpected shutdown or  service restart. etc... ..

one time i see event viewer but after the failure of DB system restart

Can you tell us the full event with ID?

event id is 513
and message is
windows is shuttingdown and all sessions will be terminated by this shutdown

Before to this any error?
How is your SEPM now?Working fine?

its working fine now, tell me can i move from embeded DB to MS Sql

It is possible
Refer this KB
Symantec Endpoint Protection Manager:moving from the Sybase Embedded Database to Microsoft SQL Server

i run the support tool it shows the error
see the attached file

I am not able to find the attachment....

i think there is some problem is present with IIS.Reinstall IIS and do a repair for SEPM from add/remove programs....

Error SEPM Virtual Directories with incorrect permissions: Location Expected Actual
/LM/W3SVC/1/ROOT None Scripts only
 

Error SEPM Virtual Directories with incorrect paths: Location Path
/LM/W3SVC/1/ROOT c:\inetpub\wwwroot
 

Error No SepM IIS virtual directories exist which are properly located in the directory C:\Program Files\Symantec\Symantec Endpoint Protection Manager\Inetpub\. Check the report "Is Microsoft IIS correctly configured for Symantec Endpoint Protection Manager?"

These errors shows by support tool

Can you  paste/attach the scm-server-0.log with is present in Program Files \Symantec\Symantec Endpoint Protection Manager\tomcat\logs. 

2010-07-30 10:29:39.343 SEVERE: ================== Server Environment ===================
2010-07-30 10:29:39.343 SEVERE: os.name = Windows 2003
2010-07-30 10:29:39.343 SEVERE: os.version = 5.2
2010-07-30 10:29:39.343 SEVERE: os.arch = x86
2010-07-30 10:29:39.343 SEVERE: java.version = 1.6.0_14
2010-07-30 10:29:39.343 SEVERE: java.vendor = Sun Microsystems Inc.
2010-07-30 10:29:39.343 SEVERE: java.vm.name = Java HotSpot(TM) Server VM
2010-07-30 10:29:39.343 SEVERE: java.vm.version = 14.0-b16
2010-07-30 10:29:39.343 SEVERE: java.home = C:\Program Files\Symantec\Symantec Endpoint Protection Manager\jdk\jre
2010-07-30 10:29:39.343 SEVERE: catalina.home = C:\Program Files\Symantec\Symantec Endpoint Protection Manager\tomcat
2010-07-30 10:29:39.343 SEVERE: java.user = null
2010-07-30 10:29:39.343 SEVERE: user.language = en
2010-07-30 10:29:39.343 SEVERE: user.country = US
2010-07-30 10:29:39.343 SEVERE: scm.server.version = 11.0.6000.550
2010-07-30 10:29:43.250 SEVERE: ================== StartClientTransport ===================
2010-07-30 10:29:43.750 SEVERE: Schedule is started!

As per the log server is working fine.but still you can increase the log level and see any error is appearing.
For this go to C:\Program Files\Symantec\Symantec Endpoint Protection Manager\Tomcat\etc\conf.properties Set scm.log.loglevel=fine.....

i put a mannual entry in mentioned file

also update me about the IIS errors that i locate before this

Refer my earlier link.That link currently you may not be able to access because of some problems in symantec KBs.Try after some time.....

how can i set the DB cache size

Right now what is the exact problem you are facing?