Even though you think it has... Please look at this thread Thumbnail Cache Randomly Deleting and Recreating This bug is a common one. Please take notice!

This problem probably happens due to the fact that there is a maximum siize for the thumbnail cache. Microsoft needs to take into account that a lot of users nowadays have up to hundreds of thousands of PDF, JPG and other documents that use thumbnails and 449 Mb for each thumbs.db file is not enough. Please remove this file size limit from Windows 7.

On Fri, 11 Mar 2011 21:58:03 +0000, bmac2 wrote: This problem probably happens due to the fact that there is a maximum siize for the thumbnail cache.  Microsoft needs to take into account that a lot of users nowadays have up to hundreds of thousands of PDF, JPG and other documents that use thumbnails and 449 Mb for each thumbs.db file is not enough. Please remove this file size limit from Windows 7. This isn't Microsoft you're addressing; this is a peer support forum. We are all just users of this version of Windows here, helping each other if and when we can. We are not Microsoft employees (not even those of us with "Microsoft MVP" behind our names; that's an honorary title for having provided consistently helpful advice) except for an occasional employee. If you want to complain to Microsoft about something, please contact them directly. Trying to do it here is just a waste of (figurative) breath. Ken Blake, Microsoft MVP

Hi, Thanks for your feedback, we appreciate your efforts and suggestions. To report this feedback, please visit Microsoft Connect: Microsoft Products Accepting Bugs and Suggestions Have a nice day. Alex ZhaoPlease remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.