Weird box flashing up

hey guys i hope you can help me. I have been getting this box appearing and disappearing on my mac when surfing the wed and even sometimes when not. All i can make out is the yellow caution triangle in the box before its disappears and i have no chance of reading it. Any ideas what it could be or what i could do to stop/fix it? Any help would be great thanks

Do you have Little Snitch running ??

not as far as i know. how do i check? the box appears and disappears literaly with 1-2 seconds

Little Snitch is a App so if you have installed it, it will be in your Applications Folder and a little network monitor in your Menu Bar.

nope had a look and its not there