I'd make sure you have updated video drivers and the newest direct x just to cover what causes most basic game errors. Also download ALL of the game patches from the diablo website... there may be some bugs and whatnot with your video card or sound or something that just isn't jiving without the patches. Does your computer meet the recommended system specs or just the minimum? The second error could be a virtual memory or Ram issue but if it's isolated to just diablo 2 it could quite possibly be a game specific problem. If all else fails I would post about it at
Diablo 2 tech support forums or
Open Tech's Diablo 2 area. If it pops up at other times while you're running memory intensive applications you might want to give us some more info about your system, ram, processor speed, etc.