Upon review, the problem is very likely due to using the GW Client 6.5.0. As a ‘.0’ release, it had some serious issues we had to try and work around. Upon review of the code, the work-around had to use some clipboard functions and probably explains the problem you are seeing.
As 6.5.5 has just been released, I recommend that you use the latest client software. It will very likely solve your problem and a number of other client issues too.