[General Questions and Answers] 94q45t:
Solved another way

Had the same problem with my Verizon S3. Tried the usual uninstall/reinstall with no luck, then got on the Samsung tech support chat site with "Nadia". Here is what we did (and it took some trial and error). Turned on debugging mode, drivers automatically tried to reinstall and failed again, then I switched the USB port (from one that supports faster charging to one that supports USB 3.0), the drivers reinstalled again, and it worked. Here is the chat transcript:

info: Please wait for a Samsung Agent to respond.

info: You are now chatting with 'Nadia'. There will be a brief survey at the end of our chat to share feedback on my performance today.

info: Your Issue ID for this chat is LTK56401322851X

Nadia: Hi, thank you for contacting Samsung Technical Support. How may I help you today?

Visitor: I have tried to install the device software on my Windows 7 PC to support the Verizon Galaxy S3. I keep getting "SAMSUNG Mobile MTP Device Failed" errors. I have uninstalled the drivers and software, rebooted, and reinstalled three times with the same result. This is a Win 7 64 bit machine. Any ideas?

Nadia: I understand that you have an issue downloading a software on the device. Is that correct?

Visitor: No. I have the software. The problem is that it will not install on my computer properly. As a result, my PC cannot see the phone when it is connected to the USB port.

Nadia: Thank you for correcting me.

Nadia: Are you referring to SCH-I535?

Visitor: yes

Nadia: Thank you.

Nadia: May I know if the USB debugging mode is ON on the phone?

Nadia: Please check mark USB Debugging option under Applications >> Settings >> Applications >> Development on the device.

Visitor: no it is not

Nadia: Please check mark the USB debugging mode and try.

Visitor: I have turned it on. Is that what you want?

Nadia: Yes.

Visitor: The PC now is trying to re-install the drivers

Nadia: Let me know if the drivers are reinstalled succesfully.

Visitor: The USB composite device, mobile usb modem and ADB interface were successful. The Mobile MTP Device failed

Nadia: Please right click on MY Computer>>Select Properties>>Hardware>>Device Manager>>Click on Samsung USB drivers and click on Update.

Visitor: Windows says it is up to date.but the device status is "the device cannot start (code 10)"

Nadia: Okay. Please perfrom the below step while the debugging option is on and try to connect.

Nadia: Please follow the steps mentioned below to perform a soft reset on your Phone.

1. Turn off the handset.

2. Remove the battery and wait for 30 seconds.

3. Reinsert the battery and turn ON the device.

Visitor: ok

Nadia: Please perform the above steps and let me know the status.

Visitor: Just removed the battery I have short fingernails and it is difficult to get the back cover off.

Nadia: I am sorry to hear that.

Visitor: just restarted it

Nadia: Okay.

Visitor: shall I reconnect it now?

Nadia: Yes. Please connect it and let me know the status.

Visitor: It's trying to reinstall the MTP driver.

Nadia: May I know if the installation is successful?

Visitor: Computer is still thinking

Visitor: Failed. Windows says the device cannot start

Nadia: May I know if you are using the USB cable which came along with the device?

Visitor: yes

Nadia: Okay.

Nadia: Please give me a moment while I go through the inquiry.

Visitor: ok

Nadia: Please try to connect to another USB port of the PC and check?

Visitor: ok

Nadia: Thank you.

Visitor: That worked!