Freebsd won't boot

[Peter James]

I loaded and installed Freebsd and got it running.  When I came to log out I used the exit command to exit as user, and then for want of being able to 
find any other command just switched the computer off.  At this point I was at the login? process. 
When I tried to boot-up this morning I get the following error messages, repeated time and time again:-
Phase1 check blocks and sizes
Phase 2 check pathnames
Phase 3 check connectivity
Phase4 check reference counts
Phase 5 check cylinder groups

This process seems to just run and run, with no end.  What do I do from here?  Any help or advice greatly appreciated.
Peter F James
please reply to: pfjames at pingu.co.uk