Doom on my Ubuntu

Hello there!
Since I've changed my OS from Windows to Linux I have problem. When playing nothing weird happening but when I open console or chat it freezes. The only thing I can do is moving by my mouse. It's impossible to close chat/console or open menu. Please, help me...

If it can change something, I send information about my computer:

Procesor:Pentium(R) Dual-Core CPU E5200 @ 2.50GHz × 2
Graphics:GeForce 9400 GT/PCIe/SSE2
OS:64 bit
Version of Ubuntu:15.10
Version of Doomseeker:Latest



(PS:I am tired of logging out or restarting PC)
;( ;( ;( ;(

And which source port?

You can switch to a virtual terminal via Ctrl-Alt-F# where # is a number from 1-6. Login as your user, and then kill your own process. Then find the # where your graphical server is on. If the resolution is incorrect, use "xrandr -s WxH" where W is your horizontal resolution and H is your vertical resolution.

You would then not need to logout or restart your system.