I am using Moodle 2.8.5+ and have tried both recent versions of Grade Me, 2.8.0.3 and 2.8.04, and I am experiencing the same problem with both of them where the normal Grade View of assignments does not work correctly.

When first installed Grade Me seems to work and the Moodle Grade View page also. However once students start adding submissions, I get four possible results when trying to go grade an assignment via the Grade View page.
1. Sometimes I will get the correct student page for grading.
2. Sometimes I will get the wrong students page for grading.
3. Sometimes I get a page with no formatting and a warning about, "Coding error detected, it must be fixed by a programmer: Row is out of bounds for the current grading table: 5" The number at the end changes for different students.
4. The fourth result is that sometimes I get a debug message about Undefined offset and "Coding error detected, it must be fixed by a programmer: PHP catchable fatal error."