I received a package from Pocket Wizard with my three Plus II's back from repair. I was unable to determine which one (if any) was malfunctioning because they acted so unpredictably. The verdict is in.... two checked out fine and they replaced the circuit board on the third.
I'm really digging the off camera thing, so I bought up a few Nikon flashes on ebay to use with PW's in case the Canon interference problem is/was a significant problem... still not totally sure on that one. I was planning to buy two more Canon flashes, anyway, so I'll just stick with the ones I have for on camera and use the Nikons off.
I posted in the other thread about the unreliable triggering I have been getting from my PWs as well. I use a 430EX usually as my PW slave flash and have been unable to get reliable firing lately from further than 30 feet. I've replaced the batteries and other troubleshooting methods. I'm going to borrow a non-Canon flash from a buddy to also check out this interference thing.
I'm still at a loss to figure out why you were having errors. I don't think I've ever had a single misfire where my PW's were responsible, triggering my Dynalite, Profoto, and Elinchrom packs, nor modified 580EX or Nikon SB-xx flashes. This is in every setting (indoors, outdoors, forest, mountains), every range (2' to 250'), and every conceivable environmental situation.
The only misfires I ever had were traced to a failed sync cord that was promptly thrown in the trash, and I then ordered 3 spare cords of each type that I needed from flashzebra and stashed them in my various bags.