I encountered a PC earlier this week where the notification area was full of blank icons. It acted like it had icons in the system tray but they didn’t react to clicks or right-clicks. It wasn’t that alarming when the notification area was collapsed but when it was spread out on the task bar, it certainly looked odd.
Fortunately, a quick search on Google turned up a freeware tool that will clear the system tray cache. Notifications Area Cleaner for Windows 7 is a small download and it runs quickly. It clears the registry setting and restarts the Explorer process. Suddenly, all the icons were back.
When the option to reset system icons and any of the other notification area options wouldn’t clear this issue, I was happy to find the tool that only took a single click to fix the problem.