A flaw discovered in the recently-released Windows Home Server earns a big whoops, in which user data is at risk for corruption. Microsoft has warned users that editing files stored on a Windows Home Server and then saving them could result in corruption, ranging from Office documents to Quicken files, pictures, torrents and more.
The problem, Microsoft says, is a flaw inside Windows Home Server's shared folders. That's a tough break for anyone using the suite as a backup solution, though Microsoft is currently working on a fix and likely with one of this severe of a nature it will be part of the next patch cycle (We hope). There aren't any workarounds mentioned at this time.
In the meantime, if you are using Windows Home Server, be careful of editing files "on the fly" across your network - and always, always keep a backup. Then again, that's what WHS was intending to do in the first place - give you a backup.