I get this a lot, as do my users on their machines. Periodically you will open the layer properties box and although the window opens, it is blank. Although if you click on , say, 'freeze a particular layer', it will still freeze as though it was displayed. We find shutting and reopening AutoCAD solves the problem, but it is an annoying glitch. We are using MEP 2012 currently.
This applies to older versions supposedly, but it may offer some help.