Text in Torchlight on Linux disappear when leveling up

I have a bug in Torchlight Humble Bundle Linux. When I level up and want to select the upgrades the fonts of the whole screen change when it's run with sudo to blocks and when it's run without sudo they disappear.

As you can see the faces also disappear but this is a known bug and it doesn't change the game's playability. But the disappearing fonts are really annoying. How do I fix this?

I am using Linux Debian Wheezy 64 bit.

It looks like whole font was wiped out of memory. I don't know if it helps but I found this on https://pcgamingwiki.com/wiki/Torchlight

Upgrade the kernel and/or reinstall fglrx-driver for AMD video cards

I was unable to find anything more. Hope it helps.