Re: Arduino / USB association on Lab PCs (non-admin users)
In a nutshell, yes, we are seeing problems on machines with existing UNO installs.
Yes, the arduino-1.0.1 (which includes the "\drivers" subfolder with .inf files) are installed on all machines. Although, as you know, there is not really an "installation" with arduino, per se, it's just copying the files to "C:\Program Files (x86)\arduino-1.0.1\"
Your statement beginning with "Usually" was our experience in the past. However, with this current batch of 250+ Adafruit/170 kits containing R3 boards, this is not the case. Device manager correctly identifies less than 30% of the boards. Students are not admins on the lab PCs, so at that point they can't do anything. A faculty or TA must come over to the PC and do the Device Manager, Update Drivers procedure using their admin credentials in order to recognize the board. For that specific PC, we then find subsequent students have about a 50% chance of their board working. When one doesn't work, the process is repeated, and so on... A complete waste of class time.
So we went back to our initial "installation" arrangement to re-do it. As admin, we installed Arduino software and connected not just one R3 board, but three R3 boards in succession (3 boards that we had previously marked as apparently "different" from each other.) Each was automatically recognized and assigned a different COM port as you mention. When we re-deployed this new installation, however, students still have the same problem with a few of the boards (perhaps 20%). This suggests that we must have "missed" a variety of R3 board and needed to connect a fourth or fifth variety of R3 during the initial installation process.
This seems crazy to us, that there would be "versions" of the R3 board that are recognized differently by Windows via USB. We're looking for an explanation to this, in hopes of developing a better procedure for the students to use these in a lab situation.