Text won't stop deleting, delete key appears to get "stuck"

Question

Sorry if this is in the wrong topic, I have never used the support forums for any of the multitude of problems I have had with my Mac, but this one is severe and odd enough that I couldn't even find anyone else discussing it (although I'm sure someone is, but I tried many search key combinations on Google and only found unrelated things), so I decided to at least get it documented.
I have had an issue that has happened at least 3 times I can remember (I am fairly certain it has happened more, closer to 7-8, those are just the times I am 100% confident about), although very spaced apart and infrequent, where my delete/backspace key seems to get "stuck". However, at least one time I can verify that I never even hit the key. Whatever text I currently have open immediately starts deleting at lightspeed, and I can do nothing to stop it. None of the other keys on my keyboard work, and though my mouse works, if I click somewhere else, it starts deleting the text there. When I force it to go to another window where there isn't an open text box, I get the general Mac error sound, and it repeats non-stop, and faster than I've ever heard it. I have to do a hard shut-down, although once it led to a kernal panic. When I have stopped whatever is happening before it panics though, when I restart, I don't receive any kind of error message, nor the message about OS X not having been shut down properly.
Every single time it has happened when I was typing something that couldn't be saved, like a message on a forum, a private message on a site or an IM chat window. Sometimes I lost a half hour's worth of work or more.
The first time it happened, I honestly thought someone had managed to hack into my computer, but another time I was using a physical modem and Airport was turned off, and when I ripped out the cord, it didn't stop.
I have a MacBook Pro from 2007, running the most recent version of Tiger. I haven't had the money to upgrade. All security updates are up-to-date, with one exception: I have not upgraded to the most recent version of iTunes.
Honestly, I currently am having and have been having a bunch of other severe issues with my Mac, so troubleshooting will be quite difficult as it's not at all impossible it's a result of one of my other problems. I also currently am dealing with some health problems that make me unable to try to find the root of the problem, specifically I have a problem with my hand and wrist that makes typing very difficult.
If someone does recognize this issue and already knows why it might be happening, I'd appreciate the help. I'd also appreciate anyone letting me know how I can prevent it OR what to do when it begins and how to stop it. But I probably will be unable to go through a typical troubleshooting rundown.
As I said, I just wanted this documented, and I also would like to know if anyone else has had this problem. I have never experienced an issue like this with any of my past computers, including Macs and PCs. I do know however that the key is NOT physically getting stuck - as in getting lodged down and continuing to be pressed. There is at least 1 time I can verify I never even hit the key (I wasn't typing anything at the time). I am fairly sure the problem is entirely unrelated to the actual delete key itself.
I'll describe the symptoms one more time:
At a random time, with no discernible warning, text contained in whatever text box I have open begins deleting itself. Several paragraphs disappear in a matter of seconds.
Pressing escape or any other key on the keyboard does nothing. If I click to another area in the text, it will immediately begin deleting wherever I have placed the cursor. If I go to another window with text that can be edited, it begins deleting there. It does not delete in more than one place simultaneously.
If I bring another window without any kind of "deletable" text to the front, one of the general Mac error sounds (I'm not sure which one it is) starts happening and repeats without stopping at a rate that could induce a seizure. To stop it all, the only thing I have found can be done is a hard shut-down. Another time it continued to end in a kernal panic. I wish I had the details of the error, but it was so long ago and I have no idea which panic is the right one in the logs.
I have no way of knowing what programs were running at the time, as obviously that's not something I'm able to pay attention to when it happens, and it has happened so randomly and infrequently it's nothing I've been able to document. Since I have to restart to make it stop, I've then lost that info and I have no time to try to write it down or something beforehand.
I have not had any similar issues that I know of (for instance, for the "g" key keeps repeating and won't stop typing "g's") and I've never experienced this on any past computer.
Thanks for anyone who can help!
If you aren't able to offer advice but have had this issue yourself, PLEASE let me know. I can't seem to find anyone who has experienced this particular problem.

Answer 1

"Cleaning the keyboard is the first step in troubleshooting sticky/stuck keys."
Okay, I guess I misunderstood, although I am still confused. You're saying that since the other user did an extensive clean of their keyboard and this did not solve the problem, it is "most likely" a hardware problem, correct? Wouldn't a thorough cleaning without any results show that it's probably not physically related to the keyboard?
"The "delete" key may be defective or the cover you are using somehow is making the key stick. If you have ruled out the latter and everything else, your only other alternative is to take the MBP to your local Apple Store or AASP. The staff will check out your keyboard (free) to confirm if you are having a hardware problem. If you have AppleCare or ProCare, the repairs will be free. If not.................."
Well, I had just said in my most recent post that it has now happened with other keys, and in my initial post that it happened at times when my hands were nowhere near the keyboard. It is not a defective delete key and the cover is not making the keys stick - it doesn't adhere to them and does not have any sticky substance on it of any kind. I am an experienced computer user, and I know my computer very well. While I am not a psychic that can always know what is causing a problem, I am able to discern with much accuracy what is NOT causing it.
Also, I have significant health issues so getting to an Apple store would be a huge challenge for me. And although I have AppleCare any repairs won't be free. Due to some small physical damage my laptop obtained a few years ago, I have been completely refused almost all service that I paid over $300 for, even though the damage is completely superficial. After fighting this, I was told they WOULD repair my computer, however, they would also repair the physical damage despite my insisting NOT to; I had no choice in the matter and the cost would be a minimum of $1,500 (I also would not be informed the exact price until after and my credit card would be charged without my knowledge - I had to give them my credit card number and sign away their right to make any charges and when I requested being contacted before they charged me for the repairs I didn't want done, I was told they did not do that). My family is struggling to pay for my $5 medications.
When my logic board died (that same issue that affected thousands of computer users), I had to print out Apple's report from their site, which stated that they would replace and repair them free of charge to ANY Mac owner with a computer that met certain qualifications (which mine did). When it happened, completely out of nowhere, I knew immediately that was the problem, yet still had to go through the insulting and idiotic "Is your computer plugged in?" list of things and a customer WITH AppleCare was being refused a service they'd offered to people WITHOUT AppleCare, for a known manufacturing defect that has occurred widely in nearly every brand of computer made.