Item's vault

[HissaH]

I'm playing using Steam account.
When I place or retrieve item from the vault, it works most of the time with first try. If I try to place/retrieve next item, there is about 95% chance it will fail with error saying it's impossible to contact the server (popup) or there was an error transferring item (log). At this point the whole thing appears to be FUBAR'd to the point where I have to restart the game, otherwise weird things start to happen if I try more, like item duplication. If I exit to the main menu instead, I can see the profile is logged out and the button 'Login with Steam' appears, clicking which gives error 99% of the time - "Steam client not found" (however, sometimes it will actually log in). So I quit the game, start again and transfer another item, quit and transfer another, quit...
This happens also after restarting Steam or rebooting. Sometimes (5%) I'm able to transfer few items in a row, no idea what causes that.

PS Hi everyone.

EDIT: added log