"A" key doesn't work in certain text-fields

On certain sites, (like facebook, and often google) whenever I type, if I hit the letter "a" on my keyboard, it doesn't register. So I can type my whole comment, but it will be missing all the A's. I know my A key isn't broken - when this happens, I click on the address bar and it works fine there. I go back to the comment, and it's not working. It works in IE, and it only happens with some text fields. And even then, it doesn't happen all the time.
It first happened when I got Opera 12.00 prealpha, which i stayed with until it became alpha. So I uninstalled that, and went back to using v11.52. It's still happens, & it's getting really annoying.
I'm currently on Windows 7, 64 bit. I cleared my cookies, cache, and private data (except passwords)

EDIT: It's suddenly started as I type this... This is what happens when I type with it broken: The only wy I cn circumvent this is to hold down the [a] key. nd if I hold it down too long, it will give me bunch of [a]'s, like this: aaaaaaaa. It's like it only registers if I hold it down.

EDIT 2: I fixed it. It turns out that the extension LinkRedirector was the culprit. I looked to see if anyone else reported this bug under the extension's page, but the extension has been pulled :O

Some script looking for that scancode perhaps? If it happens here then it isn't a script from the page itself, so probably userJS or an extension ...

Ummm... Im not savvy with all that scripting stuff...
So what do you reccomend I do. Should i reinstall java? Or disable some extensions?

Disable some extensions - Java has nothing to do with javascript.