The only problem I'm having lately is when I highlight areas in my post like if I want to add something into it, only to have the highlight appear again if I use the left arrow key and when I start typing again everything starts getting deleted. Using the space bar has the same result except it only goes one space to the right and won't go any further, which would be inconvenient if I want to add spaces between words in my post. I'm not sure if this is on my end or not, but I don't remember having this kind of problem before and I've done some highlighting in the past as well.. I'll experiment with this when I want to post in another thread and see if it keeps happening.
I'm using the same thing as Azuron.