On his IIS.net blog Don Raman is asking for help in testing Microsoft's WinCache caching tool because of a critical fix they had to make to the current version.
There has been several instances where people using WINCACHE have reported problem while running it on the actual production server. They have complained that WINCACHE works very well on development server but the users can see a crash (or different symptoms of it) while actually deploying it on a live production server.
There have been several reports of the issue where the site visitor gets an empty page back and WinCache will crash. For those wanting to get into the technical details, the post includes them or, if you just want to find out more about the bug, there's a few email addresses you can contact the WinCache team at.