I think this is a RAM issue... As I have big issues with Vista / 88.. series of nvidia and MxO I am stuck with my old laptop atm which is running on a 1.76 ghz centrino 512 megs of RAM and a Readon X300 Mobility with 128mb vgaram ... Pretty slow yes. So what I'm going on about, is that I often get this message too and it is mostly when (as said by ANGEI) returning to the LA / Reconstructing / switching hardline / beeing recalled. I also have this issue, when I have msn or some other programm running in the bkgrd, click the window of that programm and do some stuff with it and THEN click back in the MxO window (yes I play windowed).
So why I think this is a RAM issue, is because the RAM gets full very quickly when running on 512 megs (everybody knows that MxO uses a Sh!tload of ram) so even if you've just logged into your account and your waiting in the LA the RAM is already on 98%. If you then open another progg. and click in the window, I guess, that that programm takes it's disired RAM aswell and MxO has some sort of bug concerning this and just gives away the memory it needs. And without that memory the data and the is lost and the connection aswell.
Sorry for this complicated theory but my english ain't that good to discribe it with less word lol ...
Just an idea thou >_>