I can't duplicate it with Xubuntu 12.10 using updated Mesa drivers.
What window manager and system locale are you using?
I'm using Compiz and my locale is all set to en_US.UTF-8
Does this happen every time you run steam?
Yes everytime I run steam..but I started using this console thing only recently so I don't know if this prob didn't happen before
Maybe someone with Compiz can reproduce this?
I believe the error messages that shown in the console screenshot above were related to the bugs that I reported here which now has been fixed but the problem described in this issue is still happening..
Latest screenshot
Could this be due to the font type used to display the console cmd output?
It's possible it's font related but the rest of your text looks OK so it seems like Steam is getting some reasonable fonts.
Is this still active?
Closing pending confirmation that this still happens.
Here's what I see if I manually copy and paste the messages into text editor