Classicboard to slow in XP??

We have a performance problem with digi Classicboard PCI 8 Ports Running on Windows XP Pro SP2 on a Dell Gx280 (2.8 GHz) PC.
The Classicboard ran perfecly with the same configuration
on Windows 2000 Proffessional SP4.

Since we installed Windows XP Pro, we receive communication timeouts from the 3 industrial inktjets connected to the board. Nothing else is connected to the board. Communication is at 38500 baud.

The program sends a message to the printers every half a second and receives anwers back.

How can we fix the problem:

  • Is there an option in the driver that we need to use.
  • Is the PC because of XP requirements to slow.
  • Or is there a setting in XP that needs to be set??
  • Or is the board to slow for XP and if Yes, what is
    a good replacement board.

Please Help we have a set of five PC’s with this configuration and they need to run Windows XP.