Looking at the log files generated by SQL would help in knowing of sql is being shut down or killed. Also look at what is happening right before the time it shuts down
The logs are in this location.
C:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\LOG
There will be 6 log files, but the one without a number extension is the one you need. You can open that in notepad.
Here's that log, I assumed it would go back further:
2009-11-02 00:09:39.03 Server (c) 2005 Microsoft Corporation.
2009-11-02 00:09:39.03 Server All rights reserved.
2009-11-02 00:09:39.03 Server Server process ID is 4428.
2009-11-02 00:09:39.03 Server Authentication mode is MIXED.
2009-11-02 00:09:39.03 Server Logging SQL Server messages in file 'C:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\LOG\ERRORLOG'.
2009-11-02 00:09:39.03 Server This instance of SQL Server last reported using a process ID of 980 at 11/2/2009 12:01:09 AM (local) 11/2/2009 6:01:09 AM (UTC). This is an informational message only; no user action is required.
2009-11-02 00:09:39.03 Server Registry startup parameters:
2009-11-02 00:09:39.05 Server -d C:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\DATA\master.mdf
2009-11-02 00:09:39.05 Server -e C:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\LOG\ERRORLOG
2009-11-02 00:09:39.05 Server -l C:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\DATA\mastlog.ldf
2009-11-02 00:09:39.06 Server SQL Server is starting at normal priority base (=7). This is an informational message only. No user action is required.
2009-11-02 00:09:39.06 Server Detected 2 CPUs. This is an informational message; no user action is required.
2009-11-02 00:09:39.43 Server Using dynamic lock allocation. Initial allocation of 2500 Lock blocks and 5000 Lock Owner blocks per node. This is an informational message only. No user action is required.
2009-11-02 00:09:39.70 Server Database mirroring has been enabled on this instance of SQL Server.
2009-11-02 00:09:39.76 spid5s Starting up database 'master'.
2009-11-02 00:09:39.92 spid5s 3 transactions rolled forward in database 'master' (1). This is an informational message only. No user action is required.
2009-11-02 00:09:39.96 spid5s 0 transactions rolled back in database 'master' (1). This is an informational message only. No user action is required.
2009-11-02 00:09:39.96 spid5s Recovery is writing a checkpoint in database 'master' (1). This is an informational message only. No user action is required.
2009-11-02 00:09:40.10 spid5s SQL Trace ID 1 was started by login "sa".
2009-11-02 00:09:40.14 spid5s Starting up database 'mssqlsystemresource'.
2009-11-02 00:09:40.15 spid5s The resource database build version is 9.00.4035. This is an informational message only. No user action is required.
2009-11-02 00:09:40.30 spid8s Starting up database 'model'.
2009-11-02 00:09:40.31 spid5s Server name is 'SERVER\AMAZINGCHARTS'. This is an informational message only. No user action is required.
2009-11-02 00:09:40.31 spid5s Starting up database 'msdb'.
2009-11-02 00:09:40.45 Server The certificate was successfully loaded for encryption.
2009-11-02 00:09:40.65 spid8s Clearing tempdb database.
2009-11-02 00:09:40.73 Server Server is listening on [ 'any' <ipv6> 61067].
2009-11-02 00:09:40.80 Server Server is listening on [ 'any' <ipv4> 61067].
2009-11-02 00:09:40.80 Server Server local connection provider is ready to accept connection on [ \\.\pipe\SQLLocal\AMAZINGCHARTS ].
2009-11-02 00:09:40.80 Server Server local connection provider is ready to accept connection on [ \\.\pipe\MSSQL$AMAZINGCHARTS\sql\query ].
2009-11-02 00:09:40.80 Server Dedicated administrator connection support was not started because it is not available on this edition of SQL Server. This is an informational message only. No user action is required.
2009-11-02 00:09:41.03 Server SQL Server is now ready for client connections. This is an informational message; no user action is required.
2009-11-02 00:09:41.50 spid8s Starting up database 'tempdb'.
2009-11-02 00:09:41.67 spid5s Recovery is complete. This is an informational message only. No user action is required.
2009-11-02 00:09:41.69 spid11s The Service Broker protocol transport is disabled or not configured.
2009-11-02 00:09:41.69 spid11s The Database Mirroring protocol transport is disabled or not configured.
2009-11-02 00:09:41.74 spid11s Service Broker manager has started.
2009-11-02 01:00:46.62 spid1s Server resumed execution after being idle 3031 seconds. Reason: timer event.
2009-11-02 07:46:22.51 spid53 Starting up database 'AmazingCharts'.
2009-11-02 07:46:30.82 spid55 Starting up database 'Codes'.
2009-11-02 07:46:31.09 spid56 Starting up database 'Meds'.
