In my understanding the QuickWatch and the Immediate windows are executing the code / expressions under the current executing context, so once there is a using System;
in place in the code, the quickwatch window will not give any issue. You may have encountered some visual studio bug. Try restarting VisualStudio and check again.
I have not encountered this kind of issue. This kind of issue will crop up when you try to Quick Watch Math.Pow(2d, 4d); when having the code like this System.Math.Pow(2d, 4d);