This is strange, but I have encountered the very same problem in the past few days exactly as how you described it such as the words disappearing, the programs will not open, and it requires a restart for the programs to be running again. My specs are the same, around a 2005 Dell PC Windows XP Media Edition and I cannot wonder if it was a mere coincidence that this happened. I have ran Malwarebytes, Avast!, and Spybot S&D and all three of them did not detect anything dangerous nor did I find any new suspicious processes running in the Task Manager. From what I'm assuming right now, I tracked it to possibly an Avast! update problem based on the users talking in their forum.