I installed Ubuntu on my HP ProBook 4740s. When I tried to install new graphic card drivers, Unity doesn't start, or worse, I get the low graphic mode(and the screen freezes). I have tried installing the drivers directly from the manufacturer and changing the drivers in the Additional Hardware Driver menu from the default setting.
I would rather install them directly from the manufacturer.
Perhaps this is helpful:
lspci | grep VG
00:02.0 VGA compatible controller: Intel Corporation 3rd Gen Core processor Graphics Controller (rev 09) 01:00.0 VGA compatible controller: Advanced Micro Devices [AMD] nee ATI Thames [Radeon 7550M/7570M/7650M]