I've been through so many of those. Here's one: On a board, we were using an ADC chip. We bought the ICs from an official distributor. They sent us the chips,

I've been through so many of those. Here's one: On a board, we were using an ADC chip. We bought the ICs from an official distributor. They sent us the chips, and we populated the boards (~200 of them). None of the boards worked properly. We debugged for so long. After so much wasted time, we found out the root cause with the help of the manufacturer and the distributor : It turns out, the manufacturer actually produced another IC, but marked the packages with our part number. It just happened the power/gnd pins matched with our IC, so there were no electrical problems. Another case: We designed an ASIC and taped-out. The silicon arrived and we then sent it to a packaging house to get the silicon in a QFP package. The packaging house misread our specifications and placed the silicon with 90 degrees rotation in the package. That was fun to debug!