Haven't had this issue with LMDE or Ubuntu 10.04. I also used the mintUpdater for a while and then switched to apt. By itself, this isn't a problem. Yours sounds like a graphic's card issue. Is your on-board Intel graphics using a current driver? I have one of these in my laptop and had to update the firmware. Don't be too quick to re-install, you may very well end up in the same place. Hopefully someone here will have more insight about your graphics.