telnet fails when upgraded system to 300Mhz

[matyase VAX CS HSCSYR EDU]

Hi all
Here is my problem.
 I am running RH 4.2 and everything was working fine,
until I upgraded my motherboard to a 300Mhz with 256RAM 
since then telnet doesn't work at all with the 3com509TP
card. It works fine on the WIN95 partition, also at boot time it sees
the 309 card, with error messages.
Advice Please
Ed ...