After deleting a column in the Grade Center, an error is displayed that looks similar to:
errorParsingDataMsg
TypeError: ‘gpid’ is null or not an object

When the grade center is accessed the next time, an error is received similar to:
errorParsingDataMsg
TypeError: Cannot call method ‘blank’ of undefined

NOTE: This does not happen every time one deletes a column. Bb has not been able to verify the conditions in which it does happen, but says that it is only sporadic.

Status: Bb verified that this is a bug and have only been able to provide a work around. They have not said when it will be fix by.

Work around: 

Using FireFox (yes it matters)
Click on Full Grade Center
Click on Manage -> Column Organization
Reorder a column by clicking and dragging the arrows next to one of the columns (depicted as a row in the table)
Click on Submit
The grade center should now be accessible again. If you wish, you can reorder the columns back the way they were.

Reported for:  9.1 SP 5