While the basic concept is good (mouse what kills you based on what you're doing), I have several problems with this: firstly, the writing needs to be cleaned up and made far more clinical. The description of the farmer's previous Foundation involvement needs to go.
Secondly, this is not a Keter-level item. Keter is for things that, if they broke containment, would actively try to bring about the end of the world, or at the very least cause massive devastation (see: 076, 682). Safe wouldn't really fit either, as you can't just lock it away and forget about it, so Euclid it is.
Thirdly, why would the Foundation change the connector on the mouse? I don't think it's a good idea to mess around with a potentially dangerous artifact to that extent, although that's probably just me. Why not just use a PS/2 > USB converter?
Also, the effect seems unclear. See if I've got this right: if 10 days passes since last use, it translocates to some town. If you use the mouse, you can't remove it, and after 11 minutes you die, with the method of dispatch based on what you're doing. You mention that a Class-D used it after the 10 days had passed, so was he in this town that it relocates to? If it relocates to this town, why not just contain it there, under the cover of some biohazard or something?
Sorry if it looks like I'm tearing this thing apart, but I really do like the idea, and want to give as much constructive criticism as possible. Good luck with it!
Edit: For future reference, threads like this belong in the help and advice forum.