Inspiron 1420 onboard keyboard not working

There's a lot of backstory to this issue, stuff that I've tried and all, but I'll try to cut out the fluff and the reasoning and just give the relevant info:

First, specs:

Dell Inspiron 1420, Vista Home Premium 32-bit, T7500, 8400M GT(S?), 250 GB Hard Drive (self-upgraded), 3 GB RAM (self-upgraded), Logitech Cordless Elite Duo external keyboard and mouse (5-6 years old but still decent).

Now, history:

I took the computer apart for the first time about 3 weeks ago to clean the heatsink+fan - cleaning the fan required taking out the MoBo, so everything's been disconnected and reconnected - everything worked fine after the cleaning, though...

...until...

...four or five days ago, when I installed Ubuntu 9.04 64-bit in a new 15 GB partition cut from the Vista partition. The keyboard was definitely working directly before the installation, because I used the laptop without the externals to burn the Ubuntu Live Disc. I used the Logitech, however, during the installation. After the installation, the keyboard would not work with Ubuntu, Vista, or the BIOS. Yes, I have tried reseating the ribbon connection to the MoBo, about a million times now. Long story short, I've updated the BIOS, checked all of its settings, removed Ubuntu, reclaimed the partition for Vista, fixed the Master Boot Record, etc. and the keyboard still doesn't work.

The twist:

After installing Ubuntu, my computer started beeping at me after the BIOS loaded, which it still does. I can't figure out what this beeping means, and it doesn't do it every time, maybe 80%. It runs its course on its own after anywhere from four to a few dozen beeps, stops beeping, and loads up the OS. I can make it stop beeping by hitting any key on the keyboard - the one that isn't working. This has been confirmed by several repeated attempts, and isn't simply a coincidence of timing. That means the MoBo clearly sees the key being pressed, it just doesn't seem to know what to do with it.

Finally, the question:

What can I do to get the keyboard working again? My next idea (can't try it out for several hours though, since I'm at work) is to check Device Manager in Vista (funny the simple steps you can overlook...) to see what it says. However, I don't expect to get anywhere with that. Any ideas?

Edit: I got a chance to check Device Manager - it said the keyboard was working properly. I uninstalled the driver, restarted, Vista reinstalled it, restarted, and nothing has changed. On the bright side, this is all more proof that the computer actually sees the keyboard...

 

i own a 1520 and i just checked that both of our keyboards should be the same
if the device manager doesnt show any error/exclamation mark/stop sign, i dont really know what is wrong then. You can actually try running the self-diagnose hardware problem in the DELL flash screen when your PC power up. That hardware scanning test shown my HDD problem which i could finally know what went wrong, at least.
so now simply restart your pc and press 1 of the F key(idk which key, just follow the on-screen inst) and if it doesnt help, you better off ask people in the DELL sub-forum since this section doesnt have everyone using DELL

 

The last time I got a similar set of beeps was after I spilled water on my Inspiron 500M keyboard. Since you're looking at dysfunctional keyboard in the OS and in BIOS, I'd hedge my bets on a hardware issue, though it's hard to say how it came about.

Dell diagnostics is a good idea. There actually should be a keyboard test that'll show you if you're pressing keys or not; if the keystrokes aren't registering in this test, I think that replacing the keyboard will probably solve the problem. Otherwise, it's more likely a motherboard fault, and that's going to be a pain to replace.

 

Try to buy a keyboard on ebay. These are dirt cheap there.