"failed to load steamui.so" Error log below

[Ajo+]

Running Steam on linuxmint 16 64-bit
STEAM_RUNTIME is enabled automatically
Installing breakpad exception handler for appid(steam)/version(1401381906_client)
Installing breakpad exception handler for appid(steam)/version(1401381906_client)
[2014-06-23 23:37:13] Startup - updater built Oct 7 2013 12:10:55
[2014-06-23 23:37:14] Verifying installation...
[2014-06-23 23:37:14] BVerifyInstalledFiles: steam.sh is 21689 bytes, expected 23085
[2014-06-23 23:37:14] BVerifyInstalledFiles: ubuntu12_32/steam is 3448966 bytes, expected 2925416
[2014-06-23 23:37:14] Verification complete
[2014-06-23 23:37:14] BRepairInstalledFiles: ignoring bootstrap file ubuntu12_32/steam
[2014-06-23 23:37:14] BRepairInstalledFiles: ignoring bootstrap file steam.sh
[2014-06-23 23:37:16] Shutdown

How do I fix it?

I'm on Linux Mint 16

[Ajo+]

*bump*

[Axel]

Did you install proprietary video card drivers?