[racket] DrRacket/Ubuntu 12.04 LTS

Sounds like might be a problem with your Ubuntu installation or your 
hardware, not caused by Racket.  (Or the Firefox flakiness could be mere 
coincidence.)

Some things to do to try to find a non-Racket cause...

First thing to do is to test your RAM, since large programs like Firefox 
and Racket are more likely to run into flaky RAM than other programs 
are.  (If your Ubuntu installation does not have a boot-time menu item 
for testing memory, burn a memory tester CD-ROM from 
"http://www.memtest.org/" and use that.)

Then make sure that none of your filesystems are near-full, since 
programs will often crash, lock up, and corrupt data when that happens. 
(Use the "df" shell command).

There are system logs in "/var/log/" that you'll want to go through.  
Normally it's the first place I'd look, but the other things are easier 
to check if you're not familiar with the logs.  Be aware that most of 
the things that look like warning or error messages aren't actually 
bad.  You're looking mainly for kernel error messages that implicate 
flaky hardware.

Neil T. mentioned the possibility of a combination of using lots of swap 
and having a flaky hard drive.  You can search in the "/var/log/" files 
for "sd".  A "sense error" usually means time to back up your data and 
replace hard drive.  You might also see "SMART" messages in the logs; 
temperature fluctuations and such are OK, but errors are not.  Regarding 
swap, if this is a computer with modest RAM, it's not-unlikely that 
Ubuntu is creating Windows-like amounts of bloat and you're running into 
swap space.  You want to avoid getting into swap for anything except a 
last-ditch emergency measure when the kernel runs out of RAM; if you're 
running into swap, install more RAM or trim down Ubuntu desktop bloat.

Neil V.