We had a problem just like this (yesterday with three different host), but its not driver, or videocard error. These mistakes come out when we keep exchanging online maps:
http://www.pumaszallas.hu/Private/Tom/cod/beta_map.jpg
Steam integrity scan brings the errors to an end (of course, the cod version is back to 1.00.14214). If we reinstall the beta, the maps are fine untill keep exchanging again.