Office-Word is messing up, or...?

For the last five months as I type a document, random letters are appearing in the words. These are not self-made typos, (I thought it at first) they are random, often next or close to thed letter to which they are added on the keyboard - but not necessarily, (before or after).
I thought that I was losing my mind or my sight - or both, but it is not the case. (Had both checkred) I reinstalled the "Word" part of offive 2010 but without result. I even suspected my eyboard so I bought a new one (Logitech 800) in the hope of a cure: no change. I use it hard wsired although it has WiFi capability. I am at a loss as to what is happening here. Has anyone experienced this or heard of someone who has had that problem?
This is happening anywhere, in a Word document, in an email, online as here, although itis worse if I am in a Word document as opposed to online writing.
When I started to write here, I corrected the inclusions and then I decided not to. Still, I wanted the note to be rreadable so I did slow down the typing speed.
Just looking at it, it could be attributed to sloppy typing but since I slowed down to a snail pace, this is almost physically impossible to achieve unless created voluntarily!
Also, I have small fingers (size 6 glove) so using 2 keys accidentally is not an option.

I know, spell check can take care of that BUT it is getting me down because I think that I am either losing my mind or I have been jinxed.
Any help please?
Thank you in advance.