>I was actually looking at this : a problem with the constructor overloads of StreamReader
>But would have needed some time to figure out exactly how

Yes, when I read it three times, the overload pointed me to the right direction. Also, in the designer, only one parameter definition is shown but that one can take two. As is, it works. But, if within a Using, it must know exactly what we deal with.

>Keep us informed whether the extra usings solves your problem

Yes, this one is very random. It might take months before I can confirm that we never had any more occurence of such situation.