System Error Vantage 5.1 Progress 9.1c

While running purchase suggestions the server crashed and the next time
the process was run it locked on a part with the following error message
System Error: Index PLANTPOGENERATE IN SugPODtl for recid
70740590 could not be deleted. (1422)

Now every time the process is run it locks at same spot. The database
has been shut down and restarted and all purchase orders for this item
have been deleted.

Can someone tell me how to correct this problem?

Mike Thompson