Although the Token Ring card is currently not connected, having it in the
machine can cause hardware conflicts between it and the LocalTalk PC Card.
Check to make sure that the two cards are not using the same IRQ (interrupt)
line. Also make sure that the two cards are not using the same DMA channel. A
quick way to check if the two cards are in conflict is to remove the Token Ring
card. Does the problem goes away?
Another possibility is that the LocalTalk PC Card has gone bad. If you have
access to another LocalTalk PC Card, try that card to see if you get the same
results.
While you are checking for DMA and IRQ conflicts between the two network cards,
also should check the rest of the hardware in the machine for the possibility
of such conflicts. For instance, multiple serial ports could cause conflicts
with the IRQ line, which is the default on the LocalTalk PC Card.