Now im not sure if this is related, but ever since ive started using XPO, the WebDev.WebServer.exe has been crashing and Vista (on both machines) is reporting a Data Execution Prevention Error with the following details.  Im assuming msado15 being the ADO.NET library.  XPO setup is trivial, local MS Sql Express 2005 server.

Faulting application WebDev.WebServer.exe, version 9.0.30729.1, time stamp 0x488f1aa2, faulting module msado15.dll_unloaded, version 0.0.0.0, time stamp 0x4791a710, exception code 0xc0000005, fault offset 0x6fd1684b, process id 0xdc8, application start time 0x01c903a8bee7bd9d.

Could be a policy on your Sql Server.  I found a link where you can disable DEP, not recommended but a test to help you identify what is going on: http://blogs.interakting.co.uk/steve/archive/2008/01/08/Microsoft-Windows-Disabling-Data-Execution-Prevention.aspx