(Word, Excel, PowerPoint)
For many users with this black blob/dot issue, the problem is caused by a defective Bluetooth add-in for Word, Excel, and PowerPoint.
Black Blob Word 2007 FIX (Similar process for Excel and PowerPoint, just use excel.exe, and powerpnt.exe instead of 'Winword' in the following)
Thanks to MythiK on: Copy and paste in Word 2010 produces black spot | Windows Secrets Lounge !!!