When you fire a remote query using a linked server it may generate a memory dump and fail with error below
Msg 0, Level 11, State 0, Line 0
A severe error occurred on the current command. The results, if any, should be discarded.
Msg 0, Level 20, State 0, Line 0
A severe error occurred on the current command. The results, if any, should be discarded.
Resolution
1. Apply the fix mentioned in http://support.microsoft.com/default.aspx?scid=kb;EN-US;939965 if you are using OLEDB provider for DB2.
2. Few RDBMS allow index to contain column name twice. Dump the indexes of table which you are querying and check if any index has duplicate column name If you find a duplicate column name remove it. Linked server query will start working.