Garmin c550 blocked on logo, no usb recognized, plugged in usb logo appear nothing else, if i push key on and hold, the pc recognize usb port, when i let the On key, dissapear usb connection.

SOURCE: Nuvi 350 System Software Missing

Try this: Hold the power buuton down, you will see on the lower screen the word "Pre Booting - ". Keep holding the power button for about 60 second, then you will see on the lower screen "Booting".
This time, release power button; system will reboot and loading map... again.
I got the same problem, after research on the web. Nick 99990_0 had post this solution on (his Nuvi 660) but it work for my Nuvi 350 too. Good luck.

Minh (NJ)

SOURCE: Garmin Map update 2008

you will need to install the usb driver which should be located on the 2008 disk. When you attach the gps to your computer it should ask where the usb driver is located. If your dvd drive is (D) click browse and go the disk and find usb driver folder. I have purchased the new 2008 disk and had problems with it freezing on loader loading. I then browsed the disk and downloaded and then was able to get to the maps. I did not install it due to it asking what map I want to download. I wanted the whole thing so needless to say I am taking it back to walmart. I hope this helps.

SOURCE: Garmin GPSMap 60 CSx USB Connection

Actually, I just solved the problem myself...

I went to Garmin's driver download site (http://www8.garmin.com/support/download_details.jsp?id=591) and got the latest USB driver (2.2.1) for the 60C. (Although, it appears that that driver pertains to all Garmin products, not just the GPSmap series or the 60C.) Installation instructions are pretty much standard for Windows drivers, so it's easy.

That: a) Garmin requires special USB drivers for their product is finicky (most USB-connectable products just connect automatically using Windows' generic USB driver), and b) my unit -- which had always worked just fine, and suddenly stopped connecting out of the blue -- remains a mystery. Nonetheless, a driver upgrade was the final step that I needed. (Although, I also swapped USB cables and upgraded MapSource, too, so maybe it's some combination of those things.)

SOURCE: Windows XP will not recognize Garmin 200W

I had the same issue. I would plug it in and it would recognize the device then it would disappear.

What I did to solve the problem was to first turn on my Gamin 200w. After it was finished loading maps then I plugged in in to the usb port. My machine recognized the device without any problems. I am running Windows Vista Home Premium. Hope that helps.

SOURCE: I can't get my computer to recognize my Garmin 255w on USB cable.

Change the mini usb cable. Some mini usb cable are for charging and not data. It happen to me and used the externo hard drive usb mini cable and zapppppp my computer nows read the gps and gave it a drive (h:\). hope it works for you.