from the start menu i cant use my mouse to choose to start a campaign, quit or anything event though i can see the mouse, i have to use keyboard, i don't know if this is normal

in game i can use the mouse to change rirection, shoot and eveything

but when i want to use inventory, or loot something, then the mouse is not making any action : there is no mouse over providing information, and i cant drag and drop guns or anyting in the inventory. even if i can see the mouse. i noticed that some keys are allowing me to higlight some menus but i cant find any logic in that