When I cntl z it says nothing to undo. I have 3000mb for undos.
what version of 8 are you running? paste systeminfo results here-
it happens when you do certain actions which are still a bit obscure, i had the feeling these instances actually got less, it at least has been a while since i encountered them. it would definitely help if you could remember the lasts steps before that happened.
we have seen this in some versions of v8, thus the request for systeminfo-
or you can simply help>check for updates and grab the latest.