Condition affecting certain
Linux distros when they run low on
virtual memory
Caused by a duff
VM subsystem.
Let's say you're running GIMP, Netscape, XMMS, Enlightenment,
GNOME, and half a dozen instances of {YOUR_SERVER_HERE!}.
A certain website spawns a shedload of popup windows, enough to hammer your swap.
The kernel decides to swap out Netscape instead of GIMP. Duh.
Since Netscape is needed straight away, the kernel swaps it back in.
Which exhausts RAM.
which causes Netscape to swap out again.....
Rinse.Repeat.
The GUI is now locked, and the disks are starting to thrash themselves apart.
You can try to switch to a virtual terminal and kill -9 Netscape,
but usually the CPU is so busy playing musical chairs with your processes
that it doesn't have enough time for something as piffling as a root login.
What to do? Reboot the box. The Windows Universal Fix. Don't you feel cheap?
In this age of Ghz CPUs and 512Mb of RAM, this isn't noticed by a lot of people.
I run a P133 with 32Mb, so it caused me real problems, until I switched to FreeBSD.
The FreeBSD kernel is sensible enough to realise what is going on here, and will cheerfully
strangle any process that requests more RAM that the VM system has to offer.
NB: I know this comes over as an advocacy rant.
It's not supposed to be, it's just my experience.