user conflict problem

Hello All,
I am having a major problem at my website: http://www.bneiyehuda.com/temp

I have installed Simple Facebook Connect a few months ago and recently have started getting trouble by users mixed up.
What do I mean?
Many people leave comments on my name and people not purposely leave comments and it gives my facebook profile picture and name with them (like they facebook connected on me with no connection to me at all).
Sometimes when I enter the wp-admin with my login and password and login on the top right corner where it says ‘Welcome Yaron’ it gives me a different username (it logs on a different person).

I tried reinstalling and deleting the plugins and changing my password a few times.

Maybe its a database conflict or something to do with the plugin?

This is very problametic for me as people may use my good name in order to put bad comments.

Please advise urgently.
Regards
Yaron