I have an (2012) nexus 7. When I plug it into my (win7 x64) PC, the PC doesn't see it. The nexus shows that it's charging, but the PC acts like it doesn't it. I've tried multiple cables (which all work with my nexus 4) and multiple USB ports (ditto). I've multiple PCs, and I have even tried doing "wipe data/factory reset" to the tablet. It's been a while since I've tried plugging this into the PC, so I cannot be sure, but I suspect that it's the recent android update that is causing the problem. What else can I try?