Can't see selection box ticks, etcetra.

For a while now I have a problem with my Dutch 64bit W7.



None of the ticks are visible and as you can see in the highlighted area those boxes aren't showing which has been selected as well. The tick boxs in Windows Explorer that you can turn on to select items do appear however.

Has anyone seen something like this before and know of a solution?

Made a backup of Firefox using MozBackUp, reinstalled Firefox and the problem was gone.