Cisco Firewall :: ASA 5550 / Basic NAT From Outside Remote-access IPSec VPN To Inside?

I cannot get this to work properly and I've even had a Cisco engineer from TAC set-this up... and it literally broke my inside network.  I have a VPN range of addresses..x.x.x.x on the Outside that needs access to a server on the Inside at y.y.y.y.  HTTPS/443 connectivity.  I need to NAT my VPN subnet/pool in order to talk to the inside host, as that host will not accept traffic from my VPN subnet, but obviously, will accept traffic from Inside my private network.
 
The Cisco tech entered the following static NAT statement to "fix" the problem - nat (outside,inside) source static VPN Inside-Network destination static Host-y.y.y.y Host-y.y.y.y For whatever reason, whenever this is configured on my ASA 5550 v8.3(2)25 the Inside interface starts proxy arping and assigns all IP addresses on my private network with the MAC address of the Inside interface. 
 
The y.y.y.y is on a remote, routed network within my private, corporate MPLS network.  My Inside private network (Inside-network shown in the static NAT above) is x.x.x.x.  Not sure why this happens, but it kills my entire network and I have to jump through hoops to quiesce the network and get everything back to normal.I've tried to Dynamic-PAT/hide the VPN range behind the Inside interface through ASDM and that seems to do nothing.The NAT statement above will break my network. How to NAT this connection without killing my Inside network?  Or, on how to properly hide my VPN subnet/pool behind my Inside interface and back to the VPN subnet/pool.