Think, there is a little missunderstanding. Normally there is only one of this showcase modules. I just activated both showcase modules to show you, that it's not a problem caused by the K2-article itself. The GK Imageshow was my favourite, until it stopped working. Only from then I changed to the module from bang2joom. So, there can't be a style conflict between the two modules, because each module has totally different styles and I'm normally using only one of them. The only thing that the two modules share, is the module-suffix, but this shouldn't be an issue.
In my oppinion the GK-module crashed a file outside the module-folder. So this file will not be refreshed by re-installation of the module. I have to find out what kind of file or entry this is, erase it and the module surely will work again, perhaps;-)
The only thing I can say, is that the module crashed while exploring, testing and switching the styles several times. Suddenly it did not work any more.