Environment:
Operation System: Windows XP SP2
BizTalk Server: Single server installation of 2006 R2 – Evaluation Copy
Recently with ‘forced’ password change some of my BizTalk sample apps bounced with following error

Upon digging a little, I realized that primarily the SSO service [ENTSSO.exe] wasn’t started on its own (as set to Automatic) which blocked BizTalk Service BizTalk Group : BizTalkServerApplication [BTSNTSvc.exe] as Enterprise Single Sign-On Service sits as a parent service for the same. You may see following error pop-up.

In essence, following windows services are all tied to your password change (should you have used your domain account during initial BizTalk configuration)
· Enterprise Single Sign-On Service
· BizTalk Base EDI service
· NS$BAMAlerts
· Rule Engine Update Service

How to update the above services to new password?
- List all Services on your machine.
- Double-click individual services listed above and click on <Log on> tab
- Apply your new password.
Addendum
There is also a link on the Web space http://www.topxml.com/rbnews/BizTalk-Rule-Engine/re-19771_Updating-BizTalk-Server-Services-and-Accounts-After-a-Password-Change.aspx that talks about the same. This one mentions single server installation on W2003 SP1.