SPD Workflow "Error Updating List Item" while setting the value of people/user field

Problem: I was calling a SPD workflow on a custom list. Whenever workflow is called upon new list item creation, following error error logged in the workflow history in & workflow inrterrupted:

2/22/2009 1:30 PM Error System Account Error updating a list item Unknown error
2/22/2009 1:30 PM Error System Account An error has occured in Expert Contact Request.

Cause: In the workflow I was setting the value of the people/group field by picking up the workflow creator's value. If I remove this action then workflow is working fine. Means, SPD workflow is unable to set the value of Person/Group field.

Solution: While setting the value of People/Group field, don't set the value of person/people field directly, instead build a dynamic string and append -1;# to the People/Group name. Finally set the output of the dynamic string to people/group field.
Example:
-1;#domain\username

So, if you are setting the field value to “company\MyUser1”, instead set the value to:
“-1;#company\MyUser1”. The -1 is constant.