When debugging variables in Visual Studio 2010 (RTM and SP1), Professional and Ultimate editions it is possible for a variable to hold a valid value, but the debugger may report a the initialisation value of the variable, for a Decimal value this default value is 0.
We have found that using the null-coalescing operator on a method returning a nullable Decimal value can result in incorrect values being displayed by the debugger when the Platform Target is set to x64.
Decimal result = GetNullableValue() ?? GetNonNullableValue();
Full code and description, with screenshots, can be found on this blog post,