Hi Saad,
You have not mentioned if your SharePoint 2010 that you're trying to install BP 5.1 on is the Free Version of a full Enterprise edition ... I assume that your entire platform is running 64-bits, otherwise you'd not try to install the BP 5.1 version... Have you tried to install BP 5.0 on a brand new system running a 32-bit OS (like W2k3 ? Are you attempting an upgrade from a previous version or is this a fresh new deployment ?
