Computers on same subnet not talking

Hi Guys,

I have 4 servers - 10.1.1.1 to 10.1.1.6 (2 have multiple IPs) subnet mask
255.255.0.0

These servers all talk to each other and all 60 odd client machines using
DHCP (10.1.13.x) from 10.1.1.1

I added another server on 10.1.1.7 - subnet 255.255.0.0 and all computers
could talk.

I rewired my switch (HP Procurve 4104gl) which has 2x 10/100 modules and 2x
10/100/1000 modules

Now:

All of the servers can talk. All of the clients can talk to the first four
servers but only some of the clients can talk to the 5th server. DNS is
working fine as it resolves the 10.1.1.7 address from any machine but ping
times out.

I have two clients dt019 and dt020 that share a printer, can connect to the
first four servers and are plugged into the switch in adjacent positions.
They can ping each other but only one can ping 10.1.1.7 and 10.1.1.7 con
only ping one of them.

I'm assuming that this is an intellegent switch problem but I have no
experience of switches and hope that someone can shed some light.

All servers are HP Proliant 380s running win2k3 Server. All clients are WinX
Pro.

I can provide screen grabs if it will help.

Thanks

Rick