There could be some app that tracks changes and D: is used. Discussions about partition size changes are plentiful but I want to write that folk do that, bomb out and lose everything on the drive. Doesn't happen all the time but it's a given we only lose what we don't backup. PCs are not reliable enough to go without backups so you know this and know that we can't count on the partition size to be bug free.
The 5 hours sounds like what happens on HDD systems. I wish it was faster but HDDs are not known for a speedy update.
This update automatically downloaded and updated, or tried to. It took ~5 hours, failed, and then I went back to my previous version of Windows. The original error message was that my d: partition was out of space. It is. I'm not sure why this update went to d: instead of c: Is this normal? Is there a way to increase the partition size or force the update to go to c:? I have an HP Pavilion g6-2235 us notebook, 8 gb RAM, 673 gb on c: (203 gb used), 25.3 gb on d: (completely used). Thanks.