For internal reference:
As per Dev:
The libraries we use are missing a .dll file, which is usually provided by Windows. So please advise customers experiencing this error to install the Visual C++ redistributable package 2010 for Windows. It can currently be found here http://www.microsoft.com/downloads/en/details.aspx?FamilyID=BD512D9E-43C8-4655-81BF-9350143D5867
Please be aware that this fix does not require a new version of the qs2-client. But basically is a required prerequisite of this redistributable.