CRM 3.0 Workflow fails

Hi,

In CRM 3.0, there is a workflow created using Workflow manager that just creates a task whenever an Invoice is created. It was working fine until now. But now that workflow fails with below error for couple of users only.

Error in Workflow monitor:

Error Code=80072020. CRMGetBusinessId failed. Returned HR=-2147016672

Any ideas will be much appreciated.

Thanks & Regards,

Ajay Chawla