In our case, as soon as our Plastic SCM client version is above 11.0.16.7626 and we try to update our workspace with incoming changes, the same window as Settius posted earlier appears and prevents from updating. When switching to the newest changeset manually, it works, as long as there are no pending changes.
We can easily reproduce this by going back to an older changeset and trying to update the workspace through either the "X new changesets available" ribbon on the top-right or by clicking the "Update workspace" button.
edit: We're using Plastic SCM on Windows machines since a few months and the problem started to occur with the aforementioned version.
