Hello. I wonder if anyone can help me or has heard of this before. Sometimes my Macbook (2011 13" running High Sierra) won't wake from sleep, and I have to do a hard restart. And then sometimes it's fine, and other times it's really slow, but I realised, when I look in the Memory section of Activity Monitor or About This Mac, that although I have 4gb of memory installed, only 2gb is showing. So I restart the computer, doing a PRAM reset, and sometimes this clears it up and I'm back to 4gb and sometimes not. Anybody got any clue what's going on? Damned if I have...