I compiled the following simple C# program using Mono 2.10.8

public class Hello {
        public static void Main() {
                System.Console.WriteLine("hello");
        }
}

I then attempt to run it under mono and native .net

# mcs Hello.cs
# mono Hello.exe
hello
# ./Hello.exe
<hangs for ever>

If I downgrade from 1.7.15 to 1.7.14 then it runs as expected

$ ./Hello.exe
hello

I've attached cygcheck.out for 1.7.15 and cygcheck.1.7.14.out for 1.7.14.