The same happens to me as well while using TFS. Usually, when you add new files to TestComplete, it automatically gets added to the repository. However, if a file gets deleted or renamed from TestComplete, the changes are not reflected in TFS. So when you perform a check-in, TFS is looking for files that no longer exist.
Note, that the .png files are automatically generated by TestComplete for each UI control when recording or playback, and these are something you don't want to store in the repository, as there can be thousands of pictures.
The only solution to resolve this, is undo pending changes, then add the project to the repository. Or undo pending changes on NameMapping\Images folder, if you don't require the images.