CDROM stopped when workstation added to network

I have a Dell Dimension 4500 running WinXP. I have 2 CD
drivers, one of which is a writer. Both have been
working fine. I have created a small network, via
ethernet hub, with another machine that I just set up as
a Win2KSvr domain controller. The other machine has ADS
setup with one resource on my Dell 4500. My Device
Manager shows no issues.

I now have two problems regardless of whether I log into
the domain or into the old account local to my
workstation :
- the CDROM drive no longer recognizes when I put disks
into it.
- the network connection periodically drops between the
two machines.

I set up this network as a learning exercise, but I'm
stuck on both issues...

Thanks for any advise you might have.

Regards,
Richard Newman