This is likely a problem with the host machine. However, I too have noticed this after about a full day on my machine (6GiB system RAM, 512MiB video RAM). A patch that helps mitigate the problem for me: http://www.startux.de/index.php/articles/51-wine-patch-to-use-3gb-userspaceyvComment51 The patch itself may not work (old), but modifying the code or making your own patch does.
