Whenever I run the issue navigator, JIRA generates the following errors in the log (one per field):

2005-05-03 20:48:16,809 ERROR [velocity] Left side ($firstsort.field) of '==' operation has null value. If a reference, it may not be in the context. Operation not possible. templates/jira/issue/table/issuetable.vm [line 15, column 41]
2005-05-03 20:48:16,810 ERROR [velocity] Left side ($firstsort.field) of '==' operation has null value. If a reference, it may not be in the context. Operation not possible. templates/jira/issue/table/issuetable.vm [line 15, column 41]
2005-05-03 20:48:16,810 ERROR [velocity] Left side ($firstsort.field) of '==' operation has null value. If a reference, it may not be in the context. Operation not possible. templates/jira/issue/table/issuetable.vm [line 15, column 41]
2005-05-03 20:48:16,810 ERROR [velocity] Left side ($firstsort.field) of '==' operation has null value. If a reference, it may not be in the context. Operation not possible. templates/jira/issue/table/issuetable.vm [line 15, column 41]
2005-05-03 20:48:16,810 ERROR [velocity] Left side ($firstsort.field) of '==' operation has null value. If a reference, it may not be in the context. Operation not possible. templates/jira/issue/table/issuetable.vm [line 15, column 41]
2005-05-03 20:48:16,811 ERROR [velocity] Left side ($firstsort.field) of '==' operation has null value. If a reference, it may not be in the context. Operation not possible. templates/jira/issue/table/issuetable.vm [line 15, column 41]
2005-05-03 20:48:16,811 ERROR [velocity] Left side ($firstsort.field) of '==' operation has null value. If a reference, it may not be in the context. Operation not possible. templates/jira/issue/table/issuetable.vm [line 15, column 41]
2005-05-03 20:48:16,811 ERROR [velocity] Left side ($firstsort.field) of '==' operation has null value. If a reference, it may not be in the context. Operation not possible. templates/jira/issue/table/issuetable.vm [line 15, column 41]
2005-05-03 20:48:16,811 ERROR [velocity] Left side ($firstsort.field) of '==' operation has null value. If a reference, it may not be in the context. Operation not possible. templates/jira/issue/table/issuetable.vm [line 15, column 41]
2005-05-03 20:48:16,812 ERROR [velocity] Left side ($firstsort.field) of '==' operation has null value. If a reference, it may not be in the context. Operation not possible. templates/jira/issue/table/issuetable.vm [line 15, column 41]
2005-05-03 20:48:16,812 ERROR [velocity] Left side ($firstsort.field) of '==' operation has null value. If a reference, it may not be in the context. Operation not possible. templates/jira/issue/table/issuetable.vm [line 15, column 41]