I've found out that when I use flat varying int inside vertex shader and read it's value inside geometry shader, the shaders are compiled fine, but at link I get that both shaders failed to link and 2x "unexpected error". Removing line where I assign value of that varying into other variable fixes the problem. Also defining varying as float fixes it.
I've Radeon HD38700 whit Catalyst version is 2010.1105.19.41785. It's like the last good driver for my card (even though there are these bugs)...