Error while Configuring Managed Accounts in SharePoint 2010

I got a strange error while creating Managed Account. I was creating the managed account with Automatic Password Change enabled. The Managed Account did not get created and it has given the below error:

"Access denied.  Only machine administrators are allowed to create administration service job definitions of type: Microsoft.SharePoint.Administration.SPGeneratePasswordJobDefinition, Microsoft.SharePoint, Version=14.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c."

 Now when I was trying to access the link of Configure Managed Account from Central Administration it is giving following error continuously:

"Object reference not set to an instance of an object."

On checking the ULS logs it tells:
"System.NullReferenceException: Object reference not set to an instance of an object.  
 at Microsoft.SharePoint.ApplicationPages.ManagedAccountsDataSourceView.FillDataTable(DataTable table, DataSourceSelectArguments selectArguments)   
 at Microsoft.SharePoint.WebControls.DataTableDataSourceView.Select(DataSourceSelectArguments selectArguments)   
 at Microsoft.SharePoint.WebControls.AdministrationDataSourceView.ExecuteSelect(DataSourceSelectArguments arguments)   
 at System.Web.UI.DataSourceView.Select(DataSourceSelectArguments arguments, DataSourceViewSelectCallback callback)   
 at System.Web.UI.WebControls.DataBoundControl.PerformSelect()   
 at System.Web.UI.WebControls.BaseDataBoundControl.EnsureDataBound()   
 at System.Web.UI.WebControls.CompositeDataBoundControl.CreateChildControls()   
 at System.Web.UI.Control.EnsureChildControls()   
 at System.Web.UI.Control.PreRenderRecursiveInternal()   
 at System.Web.UI.Control.PreRenderRecursiveInternal()   
 at System.Web.UI.Control.PreRenderRecursiveInternal()   
 at System.Web.UI.Control.PreRenderRecursiveInternal()   
 at System.Web.UI.Control.PreRenderRecursiveInternal()   
 at System.Web.UI.Control.PreRenderRecursiveInternal()   
 at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)"

So I was bit curious what is the issue and how to solve it. I could not find why this is happening but here is the workaround of the issue.
1. First remove the managed accounts which are created with Automatic Password Change. We need to use PowerShell for this. The cmdlet to delete the managed account is Remove-SPManagedAccount -I "sp2010\spadmin"

2. Now create the Managed Account and make sure do not select the Automatic Password Change Setting.

3. Now if you need to configure Automatic Password Change Setting go and edit the managed account and change the settings. Strangely SharePoint will accepts this.