A reminder not to run it under a 64bit process. Point blank its not supported. I’ve written some code to expose BizTalk OMExplorer functionality though a web service hosted under IIS 7.0 on Windows Server 2008. In this case got to the app pool and set the “Enable 32-bit Applications” flag to true.
Also remember if using OMExplorer to for example generate dynamic receive locations from within BizTalk then the host much be configured as “32bit Only”.