Occasional blank screen

I have this occasional blank screen,

I did some searching and I don’t have wp-cache installed which might caused such a thing.

I do have feedwordpress and I did had to comment some lines out because it was messing up the ajax on wordpress.

Im also a bit worried feedwordpress might be the cause of this problem….

It happens when I haven’t been to the site for a while, let’s say 10 minutes. The auto refreshing of links is also set at 10 minutes so this might have something to do with it.

I’ve now set it to 320 minutes and see if it happens again in an half an hour or so.

Does anyone have the same issues? or some clues why this might be happening?

Apache error report shows nothing weird btw.