By default when you check-in some code in Visual Studio and choose a related work item, the work item will be resolved. Depending on the TFS template you’re using this will change the work item state. Most of the time it means that the work item state will be changed to Done/Completed/… . This is nice if you only want to check-in once when your work item is really done. But if you are like me, and you like to check-in on a regular basis, than this is annoying as you have to change the check-in option to associate instead of resolve every time:
To fix this, you have 2 options; either update the Work Item template or even better change the following registry key and set ResolveAsDefaultCheckinAction = False.
Thanks Jens(@jhelderweirdt) for the tip!