Ok, my apologies… I think I might have found the problem and I no longer think it is due to your plugin. Sorry for that and taking up your time.
My host is Siteground and although I haven’t totally figured it out yet, I believe it may be to do with the ‘memcached’ setting in the siteground optimizer. I am still testing and am now talking to Siteground but once I disabled memcached I was able to deactivate and uninstall the plugin. I still have a problem that I can’t restart memcached or my site goes offline again. This is posted for your info and for anyone that might have similar issue.
thanks and again my apologies.