I've made up some very simple boards that take a Tiny44 or 84. The first few, using 44s, programmed and worked just fine. The next 3, built with both 44s and 84s, fail to identify correctly, giving non-zero IDs that are pretty consistent but sometimes vary in one or two bits. I'm using AS 6.1 and a Dragon (latest firmware).
I've checked continuity for power, ground and the 4 ISP pins, and all is good. Parts are from Mouser, not some unknown source. Target Vcc reads back 5.2V. Anybody seen failures like this? I haven't. Kind of at a loss at this point.
BTW, if I connect one of the working boards back up, they still ID and work correctly.