Inspiron 6400 - problems with keyboard

Hey,

I'm running a Inspiron 6400 notebook and all my keys worked all fine until a few days ago when the problem occured that my "E" won't work any longer:

Usually, when writing some text, some keys were stuck or I couldn't completely press them down because of some dust or a corn beneath it. On Tuesday, when my "E" didn't react properly, I looked for something like that, so I just removed the keycap and removed the corn, also. I re-attached the cap and went on writing but it appeared that removing the corn has not yet solved my problem. So I began to remove some dust with a pair of tweezers. I removed the scissor to do so, too. 

Still, the problem remained - the "E" only reacted when I pressed it very hard. I did not remove the dust brutally and do know that I have not damaged the plunger as I knew it was very sensitive.

The problem works out like this:

- Whenever I normally (quickly) type a text, it appears that most of the time the "E" won't react.

- Whenever I push the key very hard (to make it react), an "E" may or may not occur on the screen.

- Sometimes, when I push the key very hard (and DO NOT keep it pressed), A WHOLE BUNCH OF "E"s occurs (differs between 3 and approximately 15).

So it seems to me that at some time, an "E" IS registered but not forwarded - it is "stuck". When I press the button very hard instead, all the "stuck Es" can proceed and are shown on the screen. When I hold Shift to write a capital "E", and my third point occurs, it shows "Eeeeeeee" instead of "EEEEEEEE", for instance.

I've bought the laptop in February of 2007 and wrote a lot as I work much with it. I work as some kind of a journalist and have to write a lot of (german) articles, in which the letter "E" happens to be the mostly used letter - so it might just turn out to be a usual wearout. But I don't think so: When a key is worn out, it usually doesn't react at all (or only send 1 character) - and not send 10 "E"s once at a time.

Can anybody help me? What should I do (except for getting a new keyboard)? May it be driver problems? Shall I even try to fix some contact beneath the plunger?

Thanks in advance,

Harti