I would first attempt the usual procedures for a stuck batch. Get all users out of GP and run the following queries in SQL. Itts always advisable to back up the DYNAMICS and Company database before you run any queries.
SELECT * FROM DYNAMICS..ACTIVITY
SELECT * FROM DYNAMICS..SY00800
SELECT * FROM DYNAMICS..SY00801
SELECT * FROM TEMPDB..DEX_LOCK
SELECT * FROM TEMPDB..DEX_SESSION
If you get results for any of the above - run the following:
DELETE DYNAMICS..ACTIVITY
DELETE DYNAMICS..SY00800
DELETE DYNAMICS..SY00801
DELETE TEMPDB..DEX_LOCK
DELETE TEMPDB..DEX_SESSION
This should clear up any issues where users crashed out of GP during transaction entry / receiving etc.
Try and receive the RMA again.
Ian.