Jayakrishnan,
We just got into your site to test and debug some things.
First, we turned on Error Reporting to Maximum. Then, we turned on the JomSocial profile plugin. After that, we registered a user without issue. Upon logging out and logging back in, we did run into a red-page 500 error. We never saw the JController message indicated above.
However, for the 500 error, we updated our redirection logic with some planned changes in the upcoming 4.0 release. You have a specific menu item set for Returning User Redirection, and in some configurations, this has been known to be a problem. We're hoping the change in 4.0 will fix these problems, and it seems to for what we were seeing.
Please test and let us know if you're seeing any issues. Again, we never saw the JController error mentioned above, but hopefully the red page error and it were related.
Thanks for your patience,
Alex