On occasion I'd picked up keyboard, invert it (so it is key side down) then shake vigorously while tilting in various directions. Depending on various factors (notably the habits of the user), you'll get varying amount of debris -- on a few occasions a surprising amount of debris came out. On a few occasions I'd seen stuff like paper clips fall out.

One annoying thing with keyboards nowadays is that the printing on the keytops is only on the surface, so they tend to rub off in about a month or less. Older, more expensive keyboards tended to have lettering molded into the keys. Some people have described me as having "sandpaper fingers" as keytops often end up not only blank, but show visible "dents" where my fingers have worn down the surface. Mice also tend to suffer similar fate, where after about 6 months, the buttons show spots that have been visibly worn down (this is one of the reasons I tend to get mice that are molded in color rather than those that have a plated or painted surface).

>After being burned so many times I have made it a practice to change the mouse and keyboard regularly. (Looking at the gunk on the keyboard, it's about time). They have gotten so cheap it doesn't even cost much to do so, certainly not compared to the cost in wasted time etc. when they aren't working right.
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>The late great Tom Piper and I had a running comic debate about Microsoft's Natural Keyboard. The Unnatural Keyboard, I called it. He loved them. I tried one, couldn't get comfortable with it, and wound up sending it to him. I believe it was the keyboard he was using at the time of his death. Boy, I miss that guy.
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>>Since it happened in 2 browsers I think the mouse would have been the first thing that would have occurred to me. Did have something similar years ago and more recently with a wireless mouse that had some gunk in it.
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>>My other bete noire is gunk in the keyboard having a ctrl or alt key behaving as if pressed. Very annoying and manifesting in odd ways.
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>>As to laptops with an external mouse I make it a point to turn off the touch pad completely as a spec of dust can make the mouse spastic <s>
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>>>I was experiencing strange behavior with my browser! If I moved my cursor it would often jump to a previous page or even a different tab. Often the cursor would freeze. Sometimes (less than 10% of the time) the cursor would come back to life and allow me to continue, but 90% of the time when that happened I had to turn off my computer.
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>>>I noticed that this behavior of the mouse freezing also occurred when I was in an application so I decided to take action. This is a strange remedy as was the problem but it has cured all issues with the jumping cursor, jumping to previous pages or tabs within a browser or frozen cursor. I decided to replace the mouse and it resolved all of the above issues! I thought that I would let you all know the resolution as the problems were strange and I am happy to have found the solution. Perhaps no one else will have this problem but who knows?
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>>>At first I thought that the issues were due to my IE Browser. But when I used Firefox the same things would happen. That is when I noticed the problem showing up when using applications.
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>>>Computers are so much fun! I know this to be true as I have been working with them since 1962, from main frames to hand held devices. :)
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>>>Sometimes I thing that going back to smoke signals is a good idea! :)