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I have an Ubuntu 8.04 LTS Server that we use as a web server. It's a standard LAMP stack and our site is set up in Drupal. This seems to work without a problem for weeks on end. Then, out of nowhere, the processor will lock up entirely. When it does the only choice I seem to have is to hard-reset the system.

Remote logins all become unavailable, and if I sit in front of the terminal I'm sometimes able to type in my username, but it never gets as far as asking me for the password. Because I can't get into the system I can't seem to isolate the process that's consuming all of the processor time. I'm wondering what logs I can review or what I can enable to get access to better information and track down a root cause. Ideally, if I can find out what's causing the problem I can prevent it from recurring.

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So is the CPU actually hard-locking, or is it just so busy that the system becomes unresponsive? – Ƭᴇcʜιᴇ007 Sep 14 '11 at 16:05
@techie007 - Probably just so busy I can't get anything in edge-wise. The machine appears to be running still, but entirely unresponsive. – g.d.d.c Sep 14 '11 at 16:50

Check the log files, install munin, monitor the system and clean/check the computer physically (there are some videos on youtube about how-to clean the cpu and the heatsink).

good luck!

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