1. Drive D should not be reporting low space. In the default setup, there is a registry entry to disable low space checks on D so I wonder if anyone tinkered with the stock settings or ran a registry cleaner.
2. That backup system is a failure. Please find a good one that you understand and can trust.
Drive D out of space
I have read the posts and checked my system it is not backing up to the d drive but I have no space left critically low. I use sugar sync for backup and I looked in D don't see any files other than what Microsoft put there can't imagine it is full. HELP! What to do?