I don't think this is a bug. Please make sure an instance of Steam isn't already running. Has Steam run previously? You could attempt a reboot of your system and try again.
Try running steam from the terminal. Run this command (assuming a default install): /usr/bin/steam %U
This will cause Steam to launch as normal, but with output to the terminal, and you can run any program from the terminal in this way btw.
You could open a terminal, and type pkill steam to remove any other running copies and then run steam to see if it is just a problem with a background process.
After closing the dialogues, you could post the output of "ps -A" so we can see if Steam has any running processes.
Did you have a second instance of Steam running? Is this issue still active?
Closing pending more information to indicate this is a Steam problem.
Nothing extracted yet.
When i use the launcher , those 2 messages error appeares.
Sorry for bad english. x)