You are using windows XP probably, and you are using the PCCard KTX card?
Simple.. You installed it improperly, NOT selecting the proper card when you configured it in Linx.
Boot to Safe Mode
Run Regedit
Go to the key: HKEY_LOCAL_MACHINE\SOFTWARE\Rockwell Software\RSLinx\Drivers
Delete any and all folders that list a 'KT', as in "AB_KTLIKE"
Reboot.
When you first configure the card, MAKE ABSOLUTLY SURE YOU SELECT THE RIGHT CARD FROM THE DROP-DOWN BOX!