I have seen this missing end tag error in Developer for 4.6, 6.0.1, and 6.1 webMethods IS. Is this fixed in 6.5?
When 2 developers are logged in under the same ID and editting a service from different machines the flow.xml and flow.xml.bak files do not write the complete file on a save. The bottom part of the file is missing. This becomes evident after both have logged off and get back in after a period of time. In the IS admin, under package management, you will find that the package is only partially loaded and flows have “Missing end tag” as the reason it will not load. The recovery is to delete the flow and start over or restore from backup if possible.