Happens.
Obviously the machine sees the card if some applications work but not others. But it depends what it sees it as. ie. SB, SB16 etc. Some cards come with several emulation drivers. First, re-install all the drivers that came with the card.
If that does not work, go to the card manufacturers home site and get the latest driver.
The problem might also be an IRQ sharing problem. Again, go into Control Panel and see if there is a conflict (Device Manager - view by connection in Win2K).