Map contents disappear

I have a problem with the map (big map). To see any terrain or details, I have to zoom in until the map shows about 8x8 lots. As soon as I zoom out further, the lots and all contents suddenly disappear, and I only see a blue area and the green dots that represent the inhabitants. When I zoom in again, the details appear again, at once, without reloading. It looks like turning a switch on and off. That way I can't get an overall overview covering the complete SL land. This problem has been introduced with the latest few versions because I remember that about 2 months ago, all was fine. Because I had a SL-break of some weeks, I can't tell exactly at which version it appeared first. Does anybody else have that problem?

PS. Clearing the cache didn't help, and I found no settings to cure that problem.
Horst

The map is very bad right now, only 3 (4?) closest zoom shows land , especially island sims, the big mainland shows up pretty much all the zoom, why beats me i guess its to save client from dying loading all those islands ~.~

Remember when it showed them all ram use was skyhigh when you opened map.

Thili, thanks for your reply. In my case, the mainland does not show up when zoomed out, so I don't have any idea how the mainland looks like, and how big it is. I have 1Gig of RAM, and the usage was about 60% when I tried it, so that shouldn't be a problem.
Horst