Send and Refresh Schedule - Hang with Processing... Message

We installed BPC 7.5 NW SP07, facing a strange issue.

Issue: Created an EVDRE and clicked "Send and Refresh Schedule" :

The little processing window pops up with status "Processing..." in the top left corner and it says "Executing query on server..." in the bottom left. Normally the query takes a few seconds and updates data, unusually it got stuck and never updates the data and with the popup message EXCEL HANGs. Data not updated in the application/cube.

Appreciate any inputs. Thanks.