Even though, I have reinstalled the windows and all the browsers the acceptance checkmark is still invisible.
Based on the logs, you seem to be using Chrome 21 on Windows 7 - but, uh, so am I, and I see the checkmark just fine. The only difference is I'm on the 64-bit flavor of Windows.
It's also possible you're using a different browser, on a different OS, and it's spoofing the user agent - in which case I have no idea what you're using, or what could be going wrong with it.
Until someone can reproduce this, not much I can do I'm afraid. Try a hard refresh: Ctrl+F5