Unresponsive script (not on Google)

[computerfreaker]

I'm getting unresponsive script errors; none on Google, unlike the other threads like this.

The errors are on apparently-random pages; my school e-mail account (sorry, can't give the URL) is especially hard-hit.
There are just three noteworthy things here: I'm on a very slow system, the errors only occur after I've been browsing for extended periods of time, and the errors generally occur when RAM usage is high.

Thanks!

[Giorgio Maone]

Those message should also tell the file and the line number where the script stalls.

[computerfreaker]

The messages are all over the map - some are in NoScript, some are in AdBlock Plus, some are in Firefox's chrome (browser.xml)... even the specific script varies, and the line numbers vary widely too.
If you want, I can post messages here as they show up... there are a lot of messages though.

[Giorgio Maone]

If your problem is that generalized, it probably comes either from an underpowered system or from an extensions conflict.
These resources may help:
http://kb.mozillazine.org/Unresponsive_Script_Warning
http://kb.mozillazine.org/Script_busy_o ... responding

[computerfreaker]

Thanks!

idk if it's an underpowered system or an extensions conflict; neither seems likely.

On Firefox 3.0.13, I got 0 script warnings; after upgrading to Fx 3.5.5, with nothing else changing, I've gotten showered by warnings.
Here's a typical error I got this morning: chrome://noscript/content/STS.js:128

The problem happens on my Firefox Portable (3.5.5) and my Mom's installed Firefox (3.5.5), but not on my sister's Fx Portable (3.0.13)... somehow, the upgrade to 3.5.5 seems to have broken something. There isn't much to break, though; Mom's Fx only has ABP, NoScript, and TabGroups Manager.
I'm going to guess an underpowered system, but why would a Firefox upgrade trigger all this trouble? (Don't tell me Fx 3.5.5 is eating more resources than 3.0.13... I'll be sad if I have to downgrade... )
EDIT: something else I just remembered: the problem happens a lot more frequently when the CPU usage is high (i.e. >30%) than when the CPU usage is low (<30%)... probably an underpowered (or overloaded - RAM usage is generally > 1 GB on a system with 1 GB of RAM and a 2 GB page file) system?