I'm not sure if this is a problem, but I'm having a problem with another block and thought this may be the issue.
When I go to Admin, Course, Categories, I have 9 courses listed. However, if I go to Admin, Configuration, Blocks, it says 10 instances. Also, the backup says backup of 10 courses completed. Do I have a hidden course? If so, how can I get to it. I am the only user/admin/teacher of this site. Any help would be appreciated!
remember that the main page area counts as a pseudo-course (i.e. it has its own course id and has many of the attributes of a course although not all) ... that is probably why you are getting different counts (depending on whether that pseudo course is counted in or not)