i would update to 7.6.1 and install everything for a 68k on the system 7 today page in important updates. maybe something is conflicting with it.

and like you said it can be a bad card. remoce it and blow out the slot and replace it and see if it does it again.

i had no problem with my PDS ethernet card on my P 475. it runs real good. i run system 7.6.1 with the updates from system 7 today in the important updates section for a 68k.

you might be missing a few things somewhere or got a bad pref file. or a extension is corrupt