Microsoft SSRS Data Driven Subscription Error

In trying to setup a new Data Driven Subscription, I ran across an error:

Status: Failure writing file HS_AllCourses_NoDups_Mo_2011-02-03.xls : A logon error occurred when attempting to access the file share. The user account or password is not valid.

Apparently the userid must be prefixed with the domain:

<domain>\<user name>

I found this posting on the web.