COM ports - Win2000 hangs Win 98 doesn't

Hi,

Here's my problem:

I'm using a Blue Heat/Pci RS232 8 serial port PCI card on
a dual-boot system. The card has built-in transient
surge protection. Under Windows 98 external COM devices
could be turned on and off without affecting the computer
(even when the ports were opened by an application).
However, under Windows 2000 if an application opens a COM
port and the connected device is turned either on or off
the computer freezes and only recovers after cycling the
power. If an application doesn't open the COM port, the
attached device can be turned on and off with no
problems. The driver for the blue heat card is up to
date for both Windows 98 and 2000. The application and
COM ports work in both Windows 98 and 2000. Does anyone
have a solution for Windows 2000, other than ensuring the
COM ports are closed when turning on or off attached
devices?

Thanks