I received the following advisory from HP last night. It applies to anyone using a MediaSmart Home Server:
On December 21st, Microsoft announced that in some situations, customers could experience data corruption/loss when using Windows Home Server. While this issue occurs only during specific simultaneous combinations of activities under specific circumstances, HP and Microsoft are taking this issue very seriously. MS is working hard on a fix, and HP will make sure that this fix gets pushed to all MediaSmart Server owners through the automated software update mechanism. We will also communicate additional information updates to our user base through MediaSmart user communities and Home Sever blogs.
MS is now able to reproduce the problem, and we expect that the fix will be tested and delivered in the coming weeks.
Here are a couple key things to be aware of:
- If you are operating the HP MediaSmart Server with a single HDD, then this issue should not impact you.
- This issue does not impact the data on the server from PC backups. You can continue to be confident in your automatic PC backups.
Until the final fix is available, HP is making the following suggestions to current multi-Hard Disk Drive MediaSmart Server owners:
- You should not directly open and/or edit files that are stored on the MediaSmart Server while doing any other activity such as large data transfers or media streaming. If you are doing a large data transfer or streaming and need to edit a file on the server, you should first copy the file over to a PC and then open it for editing.
- There are a few key applications that Microsoft has identified that can cause this issue when files are opened and edited directly from the server. However to be safe, HP recommends that you not open/edit files directly from the server until this fix is delivered.
- A known list of offending applications can be found on the URL below.
- HP recommends that frequently-edited and frequently-opened files be stored on both your PC drives and the server until a fix to this issue has been delivered.
More background information can be found on Microsoft’s support site on the following link: http://support.microsoft.com/kb/946676/en-us.
Just to be clear, this is not an HP-specific issue but rather is the same one that affects all installations of Windows Home Server. I’ll keep you posted if I hear news of an update.
Ed Bott 
This happened to me. Im still not sure if it was Microsofts bug or an HP hardware issue. But I got 4 red lights and lost 7 years worth of family photos. After removing both HDs I mounted the main HD on my desktop. Every file was corrupt and could not be copied or opened. I boxed the unit up and sent it back to HP today. The good news; I had set the property to keep my shared folders on two physical HDs. So I mounted my second drive, which I had added to my EX470, on my desktop. After unhiding folders I got to all of my files and get them back. I hope they fix this soon and I hope I learn to keep my file on more than one machine.
Ouch, Todd!
This sounds like a hard drive failure, actually, and doesn’t match the symptoms of this issue at all.
There’s actually a procedure for recovering files in this circumstance. Did you contact HP support before taking the drives out and manually trying recovery?
Anyway, sounds like the file duplication did exactly what it’s supposed to do.
Of course I find this after it has happened.
What I am not clear about is, if this has happened can you pull the drives and connect them to another computer and get the stuff back? And if so is there any way to get the server going again?