[Hampshire] ssh (well putty actually)

Anyone any ideas on this one?

I have just installed ubuntu server onto a box followed by an apt-get to
install ssh. If I use a newly downloaded copy of putty on a kubuntu box
it will happily ssh into the ubuntu server (on the same home network).
But if I try the same from putty on my xp laptop, I get an "access
denied" error as a result of entering my password.

Why should it work from a linux box and not an xp box? I can ssh into
another debian server on the same network, and kubuntu box. The only
other difference I can see is the xp laptop is connected via a wireless
link.

I have googled repeatedly but found nothing that solves the problem.

Philip