Refresh Site, site turns white and only see basic menu text

For some reason when I refresh my site. around the 3rd time I refresh my layout disappears and then you see a white background with basic menu text. refresh again and the layout comes back. About every 3rd refresh it repeats?

Attached is a screen capture of the issue. at 10 seconds is the 3rd refresh and layout goes white.

any idea what might be causing this?

Thanks
Mark