I had the same issue with MMX352G.....but I have already sorted it far earlier.
What you have to do....
- Uninstall Everything as It was earlier to begin from starting.
- Restart you PC
- Plug your Modem and install Software. Now it will show you message Driver installation faily. But GUI will be installed perfectly.
- (IMPORTANT) Go to C:\Program Files\"Modem Name"\Driver
- Execute "InstallDriver.exe" as Administrator. Wait... Now it will Show you Driver Installation Fail. (Don't Worry)
- Now go to Device manager.
- In Device Manager you will see 4 or 3 drivers under "Other Devices" Option having Same name.
- Right Click on First one and Update Driver with Custom Path :-
64bit :- C:\Program Files\"Your Modem"\Driver\Win7_64
32bit :- C:\Program Files\"Your Modem"\Driver\Win7_32
Now It should be install Correctly.
and Repeat the same for Remaining. Drivers
Hope It will Help you.
NOTE : Follow the Step in Sequence.