It was my mouse. It has a scroll left or right when you press left or right on the scroll wheel. I changed the mouse and it was fixed.
I'm replying to this because its in the top 10 on google. So you may want to keep this thread open as this is a real solution.
I just now had the same problem, yes it's an OLD thread, yes it's not great etiquette but on other forums of which I am a member, we live and let live. But yes, IT'S PROBABLY THE MOUSE! There are no other intelligent answers in the first 10-20 Google search links, most of which are Yahoo Answers which are usually just troglodytes responding and unhelpful. To someone having this PITA problem, this thread is a sanity saver.
I was using a wireless USB optical mouse, it has been exhibiting scroll drift which was only mildly annoying, then I booted up a few minutes ago and could not click a shortcut on the desktop, any folder I clicked highlighted the Recycle Bin, and the Start menu likewise was useless. I put in a new battery, though there was no low battery warning and no lag typical of a failing battery. When I then opened Chrome to do a Google search, everything I typed was backwards, so I typed a search string backwards to make it coherent, found a lot of useless crap, and then thought to swap out my mouse, which solved the issue, so it wasn't malware or Java or needing to switch my language settings from Western to Unicode, LOL, though that worked for some dummy. I'm now using an old RadioShack USB wired mouse that I found in someone else's box of junk long ago, but which has bailed me out on a few prior occasions of mouse input issues.
So then I found this thread halfway down the search page and finally got to it, but if I hadn't thought to swap my mouse, this thread on this forum would have saved a huge amount of frustration. Whether because of the April post or because it has been indexed by Google enough to keep showing up, it's a great help, and anyone who finds it should have feelings of gratitude to this forum, so minimal snarkiness would reflect better on the members who live here.
I expect my other mouse has dust in the scrollwheel so will check that out later.