Broken keyboard

To start you can temporarily use an external USB corded keyboard, do not use a wireless keyboard, a corded usb keyboard won't require drivers, and you can access the system straigh away. You can buy a wired usb keyboard at any computer shop for $20/$30.

After you access to your system using your external keyboard, do a backup of your data, and have laptop internal keyboard replaced. The spare is not expensive, but the job should be done by a technician, here is the replacement part: Laptop keyboard replacement for Dell Inspiron E1405

I had the same problem. My keys would generate weird characters. My solution was really easy. Delete all temporary internet content and all worthless files. Then do a disk scan and defragment. It will take a long time, but it fixed my weird problem!

If you've downloaded or manipulated large files, 1-8GB, it may mess with the virtual memory or something.

Regardless, give this a try. Hope it works. I'm on my e1405 right now!