Process Exit Code -1073741819 for syspolicy_purge_history job on SQL 2008 (windows server 2008R2 VM)

I am getting syspolicy_purge_history job failed with following error

server: Microsoft SQL Server 2008 (SP1) - 10.0.2531.0 (X64)  Standard Edition (64-bit)

windows:  Windows NT 6.1 <X64> (Build 7600: ) (VM)

It is not clustered server

Date  5/3/2011 2:00:01 AM
Log  Job History (syspolicy_purge_history)

Step ID  3
Server  server1\WINDB
Job Name  syspolicy_purge_history
Step Name  Erase Phantom System Health Records.
Duration  00:00:12
Sql Severity  0
Sql Message ID  0
Operator Emailed  
Operator Net sent  
Operator Paged  
Retries Attempted  0

Message
Executed as user: Domain1\_sqlsvc_esx. Unhandled Exception:System.NullReferenceException: Object reference not set to an instance of an object.     at System.Environment.GetEnvironmentVariable(String variable, EnvironmentVariableTarget target)     at System.Management.Automation.ModuleIntrinsics.GetExpandedEnvironmentVariable(String name, EnvironmentVariableTarget target)     at System.Management.Automation.ModuleIntrinsics.SetModulePath()     at System.Management.Automation.ExecutionContext.InitializeCommon(AutomationEngine engine, PSHost hostInterface)     at System.Management.Automation.AutomationEngine..ctor(PSHost hostInterface, RunspaceConfiguration runspaceConfiguration, InitialSessionState iss)     at System.Management.Automation.Runspaces.LocalRunspace.DoOpenHelper()     at System.Management.Automation.Runspaces.RunspaceBase.CoreOpen(Boolean syncCall)     at Microsoft.SqlServer.Management.PowerShell.CustomRunspaceConfiguration.HandleAgentJob(RunspaceConfiguration config)     at Microsoft.SqlServer.Management.PowerShell.CustomRunspaceConfiguration.Main(String[] args).  Process Exit Code -1073741819.  The step failed.

thanks in advacne