LAN card problem

Dear all
Im facing one problem in SCO 5.0.5 , its that in the server there are three LAN cards INTEL PRO 100 series but when we configure all the three cards then LAN stops working . self ping is possible but no one can ping the server. If we remove driver of any one card LAN starts working.
Is there any solution
Thanks & Regards
Charu Vyas

Maximum number of nic cards may give you some clues on what you need to do.