I installed eShop on one of my Client's sites and since it was so easy to use, installed it on another of her sites.
For the second site, when clicking "Activate this plugin" the next screen was "Server Error." I was NOT able to access the site OR Admin. I used cPanel to delete the eShop directory (in wp-content, plugins) and all was fine.
I then installed the plugin again and the EXACT same thing happened. Again I deleted the eShop folder and all was fine. However, I have not checked the database to see if it has changed so I can't be sure if deleting the folder completely removed all traces of the plugin.
The two sites are on the exact same server. The sites have very different plugins - I could try deactivating them all and see if eShop works but the Client has so much going with all of her plugins that I don't want to do that.
This is all just an FYI - I understand that not all plugins can work on all sites. I'm going to try a different plugin as obviously there is some sort of conflict for this particular WP installation.