Today we had the following error with XMesh for Maya 0.4.2 in Maya 2012. Installing SP2 solved it.
[code]Error Initializing Command saveXMesh: (kFailure): Unexpected Internal Failure
API error detected in dllmain.cpp at line 74 : (kFailure): Unexpected Internal Failure[/code]
Thank you for your report! We will look into this.
Is it possible that you are attempting to load a new XMesh build alongside an older build? That will cause the same “Unexpected Internal Failure” error that you reported.