This is a well known feature of Windows (3.1 and 95). The default
seting is for COM1 and COM3 to share the same IRQ (4) and COM2 and
COM4 to share IRQ3.

You need to check your system settings on WIN95 to find free
IRQs (I think my home machine which as 4 COM ports working AOK (and 3
Parallel ports) uses IRQ10 and IRQ12 for COM3 & 4) and set your I/O
card to use these IRQs  for COM3 and 4 (either by software
configuration  or jumpers). Reinstalling the card Win95 may recognise
and use the new IRQs or you may need to fiddle with the system config
a bit.

Brian
Brian Jones
Java Technology Centre
IBM Hursley