I recently built a new PC with Windows7 Home Premium 64-bit. After doing so, I physically moved an internal 2TB NTFS drive of shared media files from an older Vista machine into this new machine. The problem is, other network devices now see some but not all of the folders/files on that drive. Everything shows up fine on both the host Win7-64 and old [now remote] Vista-32 machines, but two remote XP machines now fail to see ~10% of the folders. Those missing appear to occur in blocks of 8-10 and are grouped alphabetically (e.g. the F's thru G's, or P's-Rs for music, but different for movies), but other than that I can't discern any distinct pattern in date, file attributes, etc. If I manually type known missing paths into Windows Explorer, the XP machines can access and play those files just fine, but upon restarting Windows Explorer they disappear by default again. (This is clearly troublesome for Media Center usage, with 10% of files randomly "gone".) What's more, a SageTV HD-300 extender box detects even fewer folders/files, and those missing are a _different_ subset of the full set (some show that don't on XP, and vice versa).
All PCs are set to show all hidden files, updated with latest OS patches, Virus SW up-to-date/no reported viruses. FWIW, the NtfsDisable8dot3NameCreation register is set to the default of "2" (per volume) on the Win7 host and all volumes are set to "0" (enabled).
I've had no luck after 5 hours searching---very frustrating!---so any suggestions are very much appreciated.