I'm using Windows XP with VIM 7.2, so far I've tried a bunch of different 7.2.x patch level versions (the official 7.2, and newer patched distributions from the 'Cream' project, without Cream, of course) all with same results.
After loading a file, during regular vim usage, I'm getting random flicker flashes, really short, sometimes barely noticeable, really frequent (every 4 to 20 seconds).
It does not happen with syntax highlighting disabled
It does not seem to be triggered for anything I do, at least directly, as sometimes just leaving vim idle (even out of focus) is enough to allow the issue to be seen.
At home I'm using a faster Windows Vista machine, with the same configuration settings (in sync using DropBox), the flicker is not really an issue, if you pay attention you could barely notice very quick flickers. So I think the issue might just be hidden.
I tried already changing "nolazyredraw", "ttyscroll=1", "nohlsearch", and similar stuff I found on the web about the issue, without luck.