I feel your pain. I've been having similar issues. My problem though is that I can't get my laptop (w/ Windows 8) to recognize my S3. When I plug in the cable, it charges, but never registers as a usb device. On my previous laptop (w/ Windows XP... which has a fried motherboard, hence new laptop) I could get it into MTP mode and do what I wanted. On the new laptop, the phone shows up in Device Manager, but not in Windows Explorer. I've tried 6 different data cables, registry hacks, various apps, sacrificing chickens under a full moon, everything. I've even had a couple very knowledgeable S3 owners and forum mods try helping and they've all had to give up (very much appreciated their efforts though).
I want to root the phone, but if I can't hook it up to my laptop... I'm dead in the water. At least from a rooting standpoint anyway. At least the phone otherwise functions perfectly.
Hope you have better luck than I.
What's up...
You know I had the same problem, and I looked everywhere but could not find an answer.
I did three things and it actually worked, now I am connected to windows 8.
First I downloaded the kies 3. Then, I used an option that says update USB driver...
This didn't work.
Second, I follow this directions from another forum.
this is just to help anyone searching for the way to have your s3 not connect as installer every time.
i searched and searched for the way to do this for the better part of 2 weeks and finally found what i needed on 3 different forums / threads so i am just putting it all in one spot for everyone to see.
open your dialer.
enter *#22745927 and enable the hidden menu.
close dialer.
open dialer.
enter *#7284# and tap "Qualcomm USB Settings".
choose either mtp or mtp+adb and hit ok.
connect usb and be pleased with yourself in your accomplishment
I TRIED THIS AND IT DID NOT WORK EITHER!
Third, newer computers have the usb 3.0 as default and they say it is back compatible with usb 2.0, however in my computer (satellite p75-a7200), I connected it to three USB ports out of four and still have the same problem. HOWEVER, one of those USB ports I connect the phone and it works immediately.
Now I can transfer files and music back and forth using the USB cable...
I really don't know if it were the combination of the three of them, or one in particular, but the thing is that it works.
Try it out it might work.