Hello,
I was making a drum track this evening, everything seemed normal.
I hit esape to be able to edit a few things and noticed renoise was
autimatically erasing the notes as it was playing.
*This happened all from only hitting escape. I reopened the project…same thing.
Started a new project, same thing! It’s probably something silly like a mode has been
turned on. This mode sucks right now cause I can’t do anything.
I need some help.
Is your Caps Lock jammed?
And do you have any IME language input software running?
I have had that problem with the caps-lock and simply solved it by turning off num-lock. Just found that out today actually, after a long time of frustration and caps-lock-anxiety. 
This problem was supposed to have been addressed, but for me it is still occuring. I use the Japanese language input on an English language OS (XP)
I have to manually select En (English) as the input language on the IME bar for the caps lock to work at all in Renoise.
If I leave it on Japanese, it doesnt even register (on a Japanese keyboard, the Caps Lock is actually access through SHIFT + The caps lock key. )
Annoying in the extreme, but it was actually fixed a while back, so I guess it was unfixed… 