Keyboard intermittently not working (wired, alum.)

I've got a wired aluminum Apple keyboard I'm using with my MBP (in clamshell mode with ext. display). Most of the time it works totally fine, like right now--I'm typing with it. But sometimes, after my MBP has gone to sleep, this keyboard stops working. I'll open the MBP, make sure it's awake, unplug and replug keyboard (directly to MBP), switch USB ports, but nothing will work, doesn't work at all.

At this point, if I switch to an older Apple wired keyboard I have, that one always works. Then, after using it for awhile, if I swap the alum. one back, it works fine. I've tried restarting MBP, resetting SMC, zapping Nvram. I also just had the logic board replaced by Apple; this problem occurred before and after that.

I would just toss this keyboard, but it works perfectly 90% of the time...never misses keys or anything, works like a champ, except for sometimes (not all the time) not at all after MBP has gone to sleep...maybe always at login?

Any suggestions would be appreciated.