Can not install Gamin USBdrivers_221

SOURCE: Garmin gps

trying to get street updates and an extra memory card / can not do it on the computor?

SOURCE: My laptop won't show my Nuvi 680 as a mass storage device

I have a couple of ideas based on the information you gave:
1. That Nuvi has an SD card slot.  If your PC has a memory card reader, you could insert an SD card into the machine, copy whatever you want onto that, and then pop the card into the Nuvi.  
2.  While the Nuvi is hooked up to the PC goto the hardware device manager (In XP right click -> My Computer -> Properties -> Hardware tab -> Device manager) and see if anything has an ! or a ? next to it.  If so, that's probably related to your Nuvi and resolving that usually involves reinstalling the driver or updating to the latest driver.
More detailed info on what you're trying to do and the result of the above could get a more specific fix.

SOURCE: update problem with Garmin Nuvi 255w

I had same problem. I called Garmin customer service who connected me to a computer rep. Garmin hooks with your computer that you have your Garmin plugged into.They can upload the proper software in no time at all.
The rep told me that after I updated my Garmin I might have turned off the unit before it completed updating the new software. You need to wait until the screen with "Where to?" appears.
It works great now. Prepare to wait on hold for a while. I waited just over an hour on Monday, their busiest day.

SOURCE: Webupdater won't detect Garmin unit

I have the same problem of the Nuvi 850 being recognized by webupdater. I downloaded 4.30 firmware update using this link http://www8.garmin.com/support/download_details.jsp?id=4043 plug the unit in and ran the update. It will ask you to disconnect once it is done. The unit will boot up after a few update progress bars. Plug it back in and launch webupdater.

Enjoy,

Fellow 850 owner.

SOURCE: my gamin nuvi 7 series keeps freezinb up on me

contacted Garmin