I have a secondary SATA HDD that suddenly became unallocated space after installing the most recent Windows 7 update. Before the update, this space was partitioned, formatted and allocated.
After the updates were applied and the system restarted I received a notification that windows found a new SATA device and installed the drivers. The drive no longer appears in My Computer. When I go into Disk Management there's no option to create a new simple volume or allocate the space (I've done this before...). I tried rolling back to the previous update, but that didn't help. Any ideas?
Security Update for Windows 7 for x64-based systems KB97220
Windows Malicious Software Removal Tool x64 January 2010 KB890830
SQL Server 2008 service pack 1
driver update for realtek rtl8168c(p)/8111c(p)
Windows Live Essentials
...none of these seem like there would be any effect on disk management, do they?
Try using the restore points to roll back before the updates. See if that brings back your drive. If it does, manually install those updates 1 at a time. If the updates caused it, then you'll know which one it was. Though, none of them look like they should've affected your drive.