The issue, to be brief, is that as I'm typing, various browser behaviour will randomly and mysteriously be engaged. I have no idea what keypresses lead to which behaviour, because I type to quickly - and it tends to be that typing slowly doesn't lead to as frequent occurrences, although this could be incorrect.

Example of things that happen: Random vertical and/or horizontal scrolling of the browser page; random copy-pasting of random strings of text at random locations within a document (ie: forum post, email - and yes, all of these factors are RANDOM and have nothing to do with what I have manually copied or have highlighted, or anything like this); random back or forth browsing, or in rare cases, random navigation to a page which is probably linked to from one of multiple tabs I may have open at the time, but I can't really tell.

This is insane - or rather, I feel like I'm insane and have no idea what's going on here. I'm generally not pressing weird keys like CTRL or ALT as I type, although certainly SHIFT is a must. As far as I know this rules out formal keyboard shortcuts, but I could easily be wrong.

Does anyone have any insight into this? I'm on RHEL 5.0, if that might matter.

If you middle click over a highlighted word in X it will copy it, so that might be one of your problems, it happens to me all the time too

I'm well aware of that. The madness is that I'm doing nothing of the sort. I'm not manually copying anything, and I'm not executing any keyboard shortcuts that I'm aware of - if they exist then they are strictly sequences of alpha-numeric symbols, which would be bloody useless as shortcuts, I think you'll agree.

Sounds like uve got an unwanted guest lol.

What happens if you sequentially press each letter on the keyboard? Is it possible your CTRL or ALT keys are stuck? Does anything interesting ever happen in any other apps?

If you're using a laptop, could you be rubbing the touchpad as you type? That could explain the scrolling issues.

This is what I thought as well - the model of my laptop is somewhat notorious for the keyboard being possessed by a malicious entity.

However, it seems to me that if this were the problem, it wouldn't be isolated to my Linux partition - I should be having these issues in Windows as well, no?

Maybe not.

Regarding the "unwanted visitor"... maybe? Is this a common thing that attackers do? I can honestly say I've never been hacked (that I'm aware of) so I wouldn't know what to expect.

FWIW, I have on very rare occasions had bizarre events happen in Firefox, similar to what you describe.
I have not pinned down the cause to one EXACT key-sequence, but I did a while back conclude that the weird events were caused by (fast typing) hitting odd combinations of the lower left CTRL and/or ALT and/or MENU keys, plus a regular key.
There are a lot of possible keyboard shortcuts in Firefox & Co., some of which you **might** be able to disable temporarily by editing in the configuration area, accessed by entering "about:config" into the URL bar.

Funny you should mention this today; just last night I tried three times to reply to a thread, and halfway through my typing, the darned page would reload unexplainedly, and my text entered would be gone.
I was nearing bafflement & frustration when I finally realized that I had earlier enabled "autoreload" on the tab

Good luck!
Sasha