Well that is an old problem that just keeps showing up....I have seen it happen a few times with different driver versions. Only way I know to fix this problem is to update your drivers and even that doesn't help all the time.
Here is a post on Nvidia's forums that tells a little about what is happening.
http://forums.nvidia.com/index.php?showtopic=108581
Microsoft elaborates more on it here:
http://www.microsoft.com/whdc/device...m_timeout.mspx