Very slow game startup and text missing in menu

Hello,

I have recently bought Galactic Civilizations III on Steam, but I cannot play it:

The game loads very slowly, does not show menu unless the left mouse button is pressed(black screen), and then there is no text in the menu(see the screenshot below).
Sometimes the game crashes before reaching the menu.
I've tried deleting K2FontData_Small.fontdata and K2FontTexture_Small.dds(the game loads faster after doing that), installing the Consolas font pack, verifying file integrity, updating graphics drivers, setting UI size to Medium, uninstalling the Crusade expansion pack, none of them helped.
Specs of my computer:
CPU: AMD A8-5500B
RAM: 8 GB
GPU: AMD Radeon R7 250
OS: Windows 7 Professional SP1 x64
The game is installed to a 7200rpm HDD(the computer does not have a SSD).