partial success - by accident
Hi all - looks like we're all having similar problems and although synaptic seems to be part of the problem, it seems the vast majority are with toshiba laptops (mine is L505D GS6000) thanks for all the suggestions but most of them center around directions which do not apply to my model - those choices are not there.
however after hours of reading, talking to toshiba, etc I somewhat accidentally stumbled upon a partial fix. at one point I went back to toshiba support, then windows support (that comes with this model), ended up with updates (windows) and saw one I'd never seen before or had updated on its own. since it had "snaptic" in the names, I said what the heck and installed it. much to my surprise it disabled the touchpad, the keyboard jumping stopped, and I just plugged the mouse back in and now it's fine after weeks of getting worse and worse where I couldn't even compose an email.
you might try this. I'm sorry I didn't write it down but will see if I can find it. the real culprit for such a damaging bug is the manufacturer. if we weren't all so busy we should combine forces, send a letter to the ceo, and all sign it. but anyway, see if you can recreate what I did. I can't tell you what a relief it is. I was like the other two commenters who were ready to pull their hair out. and this laptop was halfway to the dump.. good luck!