OK, I tracked the problem down.
There is an issue with an MS update that can cause text quality degradation in certain scenarios. In this case it’s a problem with Times New Roman font which so happens to be the default font used when posting in the text window on this site. The culprit is Microsoft update kb3013455 which can cause font rendering issues on Vista. This update, as it so happens, was updated on 02/15/2015 on my computer, and more likely than not some others computers here who are experiencing the same issue and corresponds to the time when this font issue arose. The fix is easy.
1. Open Installed Updates by clicking the Start button , clicking Control Panel, clicking Programs, and then, under Programs and Features, clicking View installed updates.
2. Click the update that you want to remove, and then click Uninstall. ( kb3013455 )
You’ll then probably be prompted to restart your computer. After doing so the problem is gone! :wink: