Hi,
The following will save a lot of hair loss.

Scenario: A remote Client (600 miles away) calls and reports our software going crazy.
Characters typed on one workstations appear on the other workstations.???

Solution: As we had supplied the original hardware it took 2 days of investigative work to ascertain that the client had gone out and purchased wireless keyboards & mice.

Replaced Wireless keyboards with original and problem resolved.

The Wireless Keyboards must use the same frequency and if they are close enough pickup the keystrokes from the others.