It[edited to add the links summary as suggested] It has to do with the fact that you're using Cygwin with certain software that causes it to behave strangely on Windows. The list of problematic software is called BLODA. Check the links below for more info:
The first link is the official Cygwin definition of BLODA. Software, usually antivirus type, that implements various hooks such as when a process executes fork(), or accesses files or even memory areas. This kind of software prevents Cygwin and bash to behave correctly and the solution would be either disable the scanning by adding an exception for Cygwin's installation directory or disabling/uninstalling the software altogether.
The second link points to a mailing list problem that manifests exactly as the author of this post describes it and someone answers that question pointing to the BLODA section of the Cygwin FAQ.