The thinkorswim installer (bash script) runs, invoking a second, java-based thinkorswim installer, which runs until it invokes the GUI (X). This fails, reporting that X is not found. The installer was being executed via sudo in an xterm.
This same script ran successfully in January, 2012 on Ubuntu 10.04LTS, but does not on recent updates, having the same problem with attempting to access X. It runs successfully on Ubuntu 12.04, although there are problems after installation has completed, even with a local Sun Java 6 installed (and pointed to by the modified install script).
I have not tested this with a KDE install, only with Gnome 2.8 (Ubuntu 10.04) and Gnome 3 (openSuSE 12.2 and Ubuntu 12.04). All installs were up to date…
These problems are also discussed on Ubuntu forums at:
[java - Thinkorswim crash in 12.04 - Ask Ubuntu](http://askubuntu.com/questions/127210/thinkorswim-crash-in-12-04)
12.04 - Issues with TDAmeritrade thinkorswim - Ask Ubuntu
The crashing problem is due to open JDK 6, which spawns so many processes that it very quickly uses all available memory (even in a 6GB system). The only way to recover is to remove power – the battery from a laptop.