I know I'm rowing against the flow here, but sometimes it's necessary to use the not-so-latest drivers. There was another thread in this forum where the culprit of some problems was the latest driver. When the user (jartz) stepped back to the previous driver, the problem disappeared. Some investigation is required.

Thread was this one:
http://www.renderosity.com/mod/forumpro/showthread.php?thread_id=2753561