Oh well, administering your site is not always easy. I was setting up a new domain on my server, making use of plesk. The site that had to run on the new domain i developed on my dev server, so it was just a matter of uploading the db, uploading the files, fixing web.config, and fixing the portal aliases..... however, what i did was, inadvertedly, change the web.config of my own site to look at the db of the new site.

 

Funny enough this didnt work at all, and i didn't know i did that until some time later i surfed to my site, and it showed an error in machine.config. So, i remember doing maybe something wrong in web.config, found the error, fixed it, recycled the application pool, and the site was back online. Until i wanted to log on... none of my accounts worked..... so i checked the encryption keys in webconfig, and sure enough, they were changed (compared to the backup of web.config)... so this is why its always a good idea to keep a backup of your encryption keys at hand :). Needless to say... its working again