When did you download the k2 plugin? I'm asking because after I uploaded, I discovered that I've uploaded the wrong version of the plugin. So I reuploaded it again. If you have downloaded the pllugin last week for example, then please go again in the download section and get the plugin.
If on the other hand you've downloaded it today I would ask you to please use our ticket system(in the navigation select support->ticket system ) create a new private ticket and provide me with ftp and backend access to your site. I'll debug it tomorrow and fix the issue for you.