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It's probably a dirty or worn microswitch - open it up, read the number off the switch and order one from FleaBay, RS or Farnell. It's pretty easy to replace one if you have basic soldering skills - a minute or two is all for three pins - and it's a lot more socially responsible in terms of "repair, reuse, recycle" than binning it.
For my Logitech Trackman, the switches are D2FC-F-7N but read the existing as not all need the push contact in the same place. Last time I did it - several years ago - I got two switches for under a pound, instead of the 50 quid or so they wanted for a new unit.
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
I had a similar issue for about 2 or 3 weeks - it drove me crazy. It affected my browser windows as well as my file manipulation(open, save, copy, cut, paste, etc.) Anyhow, it just went away one day. Don't know if it was a windows update somewhere or what, but I could not fix it on my own.