My apologies upfront for a long winded response…
I, too, spent the last couple of days trying to figure out why my Droid wouldn’t remain connected to my Windows 7 (64 bit) computer. It worked the first time I connected, and then wouldn’t connect after that.
The symptoms to my problem were similar to many others: once plugged into the computer via USB, I pulled down the notifications within my Droid and clicked USB connected. I would then be promoted to mount my SD Card, which I did. The SD Card would mount for literally a second or two. I would see the “Turn off USB Storage” in the notifications (which is supposed to happen once it mounts), then would immediately receive the “Preparing SD Card” in my notifications. I could open the notifications and select USB connected again, but would continue to go through the same vicious cycle of mounting for a second, then disconnecting.
I won’t go through all the laborious steps I went through in an attempt to solve this issue, but I will say there are a lot of smart people out there in various boards, and through my painstaking research, I’ve found a workaround for me that isn’t perfect, but gets the job done and has been 100% flawless.
These are the steps I need to take each time I want to mount my SD Card to my Windows 7 machine:
1. Open Device Manager (Make sure Droid IS NOT plugged in for this to work)
2. In Device Manager, click View then Show Hidden Devices
3. Click on Storage Volumes to expand the list
4. Uninstall all hidden Generic Volumes (these are the lightly grayed icons)
5. Plug in Droid and go through the typical steps to mount the SD Card and you should be good to go.
6. As always, make sure to safely remove before unplugging USB cord once done.
The very first time I tried this, I had quite a few hidden Generic Volumes. Now that I’m doing this each time, I only have the one hidden Generic Volume that is left behind once I safely remove my Droid from my PC.
Although, I think of myself as pretty tech savvy, I really can’t figure out why this interferes and causes the problem. I’d love to figure out a resolution so that I don’t need to do this each time. Any ideas or suggestions are welcomed.