Crazy Xcode garbling with code hint

I'm having an Xcode problem, where at various times during code hinting, all the letters on the page get totally garbled and mixed around . If i select another document and then return to my initial doc, it's back to normal. This is extremely irritating, plus enervating, and i'm a bit concerned for the 开发者_JAVA技巧security of my files.

Here's a screenshot of what it looks like when its all busted. the top two lines would be where the crazy times begin.

http://tinyimage.net/share-444E_4C69B955.html

Is anybody else having the problem? and/or knows how to make it stop?

It is particularly bad when i have a constants file that i import and it code hints to extern variables in there.

Yikes! Thanks for the help!