Black Candles are bearish lines in candlestick and candlevolume charts. They signify that the closing is lower than opening for that time period.
CHKDSK, short for Check Disk, is a utility that checks the integrity of the files and file structure of your hard disk. I'll walk you through it. I have disk problems and you said I should run CHKDSK. Great.
CrystalDiskInfo's documentation on S.M.A.R.T. is a link to Wikipedia. A free utility that can give you a heads-up when your disk begins to fail is certainly worth the price. It should be noted, however, that while S.M.A.R.T. can predict some disk failures, others can come very suddenly. There is no substitute for regular backups.