Download and save this driver:
Then, disconnect from the net.
In the device manager, uninstall the Intel graphics driver, checking the box to delete the software.
Repeat the above step until you get to the Microsoft basic display adapter.
Then, install the driver you downloaded.
Then, reconnect to the net.
Now, you should know that you will lose any customizations Acer has made to the driver you had installed.
The only thing I can recommend at this point is that you remove the graphics driver (7755) that you installed earlier, and use only the graphics and sound driver provided by Acer. Those were tested by Acer. If you still have problems, Acer will need to support their laptop with the drivers they supplied.