Swep, the fault with the DynamicDNS client is due to the fact that it's looking for an older version of .net and we uninstalled them yesterday. Unfortunately, the error does not tell us which one it needs, so...
Try uninstalling .net 4 and installing .net 2 (http://www.microsoft.com/en-us/download/details.aspx?id=19) then .net 4 and see if that solves the problem.
Failing that, uninstall again and reinstall each of the .net versions in order, starting from 1.1
Jabo