I'm experiencing the same issue shown in your pic upload
It will happen with random text on a page. It appears to be a garbling of the colors. Sometimes a screen refresh makes it go away or I drag the mouse through it to make the distortion go away. Sometimes it comes right back in a few seconds. I'd posted my problem in the Computer help forum as it seemed to begin when I (reluctantly) installed IE 10. I don't use IE 10 but rarely and the issue was happening in Firefox as well. I played around with Clear Type but that didn't do anything. I rolled back my video driver to one from about 6 months ago and that did nothing. I uninstalled IE 10 and the problem seemed to disappear for a while. It returned but was not as severe. I re-installed IE 10 and it's definitely worse than with IE 9 but what that has to do with FF is beyond me. I'm not convinced that the updated browser didn't do something to the foundation of the OS that remained when I uninstalled it. Suspicion, suspicion. BTW, my PC is home built by myself about 3 1/2 years ago, runs Windows 7 Pro and has been operating flawlessly until this odd screen problem. Still, things are aging. I have another monitor I might try that. I could even restore an older hard drive image from months back but have been too lazy to do so. It's more of a nuisance than a worry right now. In any even, you're not crazy. I'm seeing exactly what you are.