fsck problem

[Alex Hunsley <lard@tardis.ed.ac.uk>]

My machine went loopy yesterday and when I restarted it it claimed I 
needed to run interactive fsck to fix things. So I did this, and all 
goes fine up to a point - (I say 'y' the fix the problems it throws up) 
- but in Pass 5 ("checking summary group information") I am prompted:

"Block bitmap differences: +(878016--878271) +(5442752--5443007).
Fix?"

When I hit 'y' to fix this, the machine just seems to hang - pressing 
return doesn't cause a newline to appear as normal during fsck. I gave 
it the benefit of the doubt and left it like this for ten hours 
overnight, but it was the same way when I went back to it.

Lastly, my / filesystem is ok, it is the disk with /home partition on it 
which has errors, so it's not as bad as it could be!

Can anyone suggest a way to progress with this problem?

thanks
alex