System locking up

[J]

On Tue, Sep 20, 2011 at 13:22, Dotan Cohen <dotancohen at gmail.com> wrote:
> I have been suffering Firefox lockups for the past few months, in
> which Firefox spikes one of my two CPU cores to 100% for about half a
> minute. I've been disabling extensions trying to find the problem with
> no success.
>
> The past few days now the whole system locks up. The mouse pointer
> moves with the mouse, but the screen beneath is frozen for about half
> a minute. After it resolves itself, I look in the KDE System Monitor
> plasmoid and see that only one of the cores had spiked. How can I
> diagnose this? Is there a way to tell it it's hardware or software
> related? The CPU temp does not rise appreciably (only about 2 degrees,
> and never goes above 50). There seems to be adequate system memory,
> and the system cooling fans are clean and spinning properly. Kubuntu
> 11.04, 4 GiB RAM, dual-core AMD processor, 32 bit PAE kernel.

Whenever I encountered issues like you're describing with FireFox, the
culprit was always one of three things:

A plugin gone bad (or poorly written to begin with)
A site running Flash
A site running Java or Javascript.

Almost without exception, issues I saw with FF were caused by one of
those three things (the last two could mean Flash or Java plugins, the
JRE, or who knows).

Ultimately, though, I ditched FF for Chrome because issues like what
you're describing, plus frequent crashes where FF would just die and
disappear and so forth were becomming daily and sometimes hourly
problems... Chrome has been far more stable for me.