That is a useful correction of what I said, but, as it happens, my advice remains the same. If, as I suspected, the issue in this case is some sort of faulty install, it needs to be cleared away and replaced. If the problem is that .NET 3.5 was never installed, then just installing it may be the answer; though that begs the question as to why the Eraser installer did not do that automatically. Either way, if Eraser works with .NET 3.5 (which ought also to be compatible with any applications that need .NET 2.0), .NET 4.0 can then be installed if needed.joel said:Actually .NET 4 is binary and API incompatible with .NET 2, which is compatible with .NET 3 and .NET 3.5 ... However, .NET 4 and .NET 2 and the derivatives are supposed to be able to coexist on the same computer, so one computer can have, say, .NET 3.5 and .NET 4 installed at the same time (mine does).