This has happened once before in another database and I erased it to solve the problem and it was with an earlier version.
In the vba code window of Access, when I try to edit text, if I open up a line of code the text will turn red and then may close the gap on its own and if I try to type some text it may rearrange this by a character or two. It almost sounds like a virus attack but I do not think so. I just think it is something that just got out of wack somewhere with the intellisence. This is almost hard to describe what is happening, but if it happened to you, you would know just what I am talking about