Oh no.. I thought I knew how to network

After yrs of running home lans and discovering over time the
peculiarities of windows networking... I'm faced with a whole new rash
of network problems... I don't know how to solve.

Following a rebuild of one of my lan machines) (Intel P4 running WinXP
pro sp/3) where I replaced the cpu... I'm now having problems
connecting to that machine from any other windows machine. (Linux and
Solaris, have no problems connecting to it).

In the Network display of other windows machines (also Intel P4s and
one is a near twin to the problem machine, all running WinXP pro sp/3)
I see the problem machine and its available shares... however I can
not access any of them.

Further from the problem machine, I cannot access shares on the
remotes either. but again can see them in the Network places display.

I made trebly sure that the disks are shared, and that I have 1 user
on every machine with the same uid and passwd. (As I always have, at
least for some yrs now).

I even went into the security settings and set allow everything for
every one, but see no change.

So the few dictums I recall are 1) make sure the disks or shares are
actually fully shared, 2) make sure all machines have at least one
common username and passwd.

I can't think of any more... but I'm pretty sure there is something
basic I'm overlooking... but like I mentioned, this is not new stuff
to me.

Things I think are ruled out are actual network wire troubles and
the two mentioned above, since networking in general works throughout
the lan.

Further I can ssh to any machine from any other... so the network is
there all around.

I think that should isolate it to the smb protocol... but maybe
someone knows better?