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.
Open Windows Explorer - select My PC - on the ribbon select Drive Tools - Manage - and click Cleanup: This is probably what will be of most interest to your particular situation: Use Disk Clean Up Utility with system files cleaning (more info on this technet blog article: http://blogs.technet.com/b/askpf...).