A Solution for: SharePoint 2007 Workflow 'Failed on start'

The Problem:
I struggled some time to get my out-of-the-box (OOB) workflow working on a MOSS 2007 environment (Win2K3 64-bit). I got always the error 'Failed on Start'. The log file on the 12-hive shows two records like this:

w3wp.exe (0x0AF4)  0x0724  Windows SharePoint Services  Workflow Infrastructure  72fs  Unexpected  RunWorkflow: System.ArgumentException: Value does not fall within the expected range.     at Microsoft.SharePoint.Workflow.SPWorkflowActivationProperties..ctor(SPWorkflow workflow, Int32 runAsUserId, String associationData, String initiationData)     at Microsoft.SharePoint.Workflow.SPWinOEWSSService.MakeActivation(SPWorkflow workflow, SPWorkflowEvent e)     at Microsoft.SharePoint.Workflow.SPWinOeEngine.RunWorkflow(Guid trackingId, SPWorkflowHostService host, SPWorkflow workflow, Collection`1 events, TimeSpan timeOut)     at Microsoft.SharePoint.Workflow.SPWorkflowManager.RunWorkflowElev(SPWorkflow originalWorkflow, SPWorkflow workflow, Collection`1 events, SPRunWorkflowOptions runOptions)

w3wp.exe (0x0AF4)  0x0724  Windows SharePoint Services  Workflow Infrastructure  98d7  Unexpected  System.ArgumentException: Value does not fall within the expected range.     at Microsoft.SharePoint.Workflow.SPWorkflowActivationProperties..ctor(SPWorkflow workflow, Int32 runAsUserId, String associationData, String initiationData)     at Microsoft.SharePoint.Workflow.SPWinOEWSSService.MakeActivation(SPWorkflow workflow, SPWorkflowEvent e)     at Microsoft.SharePoint.Workflow.SPWinOeEngine.RunWorkflow(Guid trackingId, SPWorkflowHostService host, SPWorkflow workflow, Collection`1 events, TimeSpan timeOut)     at Microsoft.SharePoint.Workflow.SPWorkflowManager.RunWorkflowElev(SPWorkflow originalWorkflow, SPWorkflow workflow, Collection`1 events, SPRunWorkflowOptions runOptions)

The Solution:
I search a lot, but didn't find a working solution. Finally I found it. It turns out that I had changed the account for the SharePoint - 80 application pool (don't remember why, but I did). But, I did this on IIS 7 and not using the Central Administration (CA).
Well, this was a wrong action. Changing the account of one of the SharePoint application pools must be done using the Central Administration (Serviceaccounts on the 'operations' page inside the CA).
And again, a big SharePoint miracle occured: the workflows started to work!