Whenever I'm playing counter-strike, or natural selection (any half life mod), after I've played for a while I get an error message that says "Runtime Error!" I don't remember the entire message, and if you need it, i'll play and write down everything it says, but sometimes it gives another error (not all the time) and it says that the memory 0x00000081 (I think) could not be read. When the runtime error occurs, the game locks up (usually repeating whatever the last sound in the game was, so it sounds like a broken record) and I can get out of the game (by ctrl + alt + del, or hitting the windows key on my keyboard), but I need to restart if I want to play the game again. Could it be a problem with the game or is it hardware related? I'm lost. Thanks.