MicroVAX/VAXstation 2000 Memory Problem

I have a MicroVAX 2000 motherboard which boots fine unless I plug in a 4MB memory expansion card. I already tried the following: [1] Attempted to boot with a different 4MB card. Doesn't work. [2] Booted a different MicroVAX 2000 motherboard with the original memory card. Worked. So, it would seem that the problem isn't with the memory card, since the card appears to work on another machine and another machine's card doesn't work on this machine. However, the odd thing is that it worked just 5 minutes ago. I know, if something's going to fail it has to fail sometime. Is there anything I should be looking for? Jumpers I should wiggle or anything like that? I'm doing this with the motherboad just sitting on the desk connected to a power supply and console cable (a special cable with pins 7 and 8 shorted) to make it a MicroVAX 2000 console cable.