Datamax label printer - problems

I have been experiencing problems with a DataMax Label
Printer - works off the serial port.

We use Bartender (by Seagull) and was fine in Windows 98.
We put a new PC with Windows XP Pro and upgraded the
Bartender software to the latest version that supports XP.
We experience problems printing the labels.

It seems to print fine - then it just quit printing w/out
any error messages. We turn the Datamax label printer off
and back on and then it works fine for a while until it
quits again.

The printer is using the serial port. We spoke to Seagull
and they don't know what the problem is. Seems to be
something between XP and the Datamax printer interface.
Which - was fine until the upgrade to XP Pro.

Any help would be welcome.

Thanks