Best Technology Thread 2008

We have held a disciplinary meeting with a member of staff. After the meeting this member of staff went home and has posted comments about the company on a social network site.

Where would we stand as a company regarding the comments made? The comments are not very favourable and totally unfounded. Could we state that they are slander and discipline this member of staff for posting these comments?

Any advice regarding any of this would be appreciated.

Thanks
Alex Grundy