Looks like the icon cache fix also worked for me. For the record, I installed no apps after start 8 and agree with the above comment that it is some how related to translucency. What I noticed was that when I was on the desktop I could see parts of the wallpaper where the icons should be.
Clean Windows 8 Pro install.
Mine only returned to normal after a restart and have never rectified themselves. It's strange, because all the other start menu apps I tried didn't have this issue and the issue only existed with start8. I have tried the fix suggest above and will see how it goes. If that doesn't resolve it, then I will unistall and use one of the other apps instead, which is a shame as start 8 is definitly the best I've come across.
I have installed the latest version, however I am experiencing issues with wrong icons in the programs menu. They seem to be ok after a reboot, but then mess up again after a while.