X11 freezes machine - have to force quit

[covehithe]

I was trying to run Inkscape when I try to run program screen goes black and keyboard disabled. (I can get program to force quit).
If I run X11 the screen still goes black and there is a now a text box labelled
XTERM in the corner and I can use all the keys in this box.
Ctrl right click gives fonts and Ctrl left click gives various commands.
Text box says "my computer" and when I enter text I get next line saying "Bash". I can quit from this box ok but I am then back to the original problem of black screen - keys disabled.
Have have downloaded latest X11 (1.3.1) dated 2006.
Running G5 10.4.11 PPC

Would like to run Inkscape - so any ideas where I should be looking to cure problem??

Thanks

[stuzog]

I have the same problem on an Intel iMac using 10.4.11 -- I can quit GIMP but the x11 screen remains without any apparent way of getting back to the Dock or the normal OS X interface. I've tried every key combination to quit.

How do I quit X11?