New Time Capsule (802.11ac) issues reading files on USB drive

Question

My 802.11ac Time Capsule reguarly fails to read .mp4 files stored on an external HDD drive connected to the Time Capsule via USB. All the files were tested as working when they were copied over, then for some unexplained reason the Time Capusle refuses to recognise them when they are accessed at a later time. This happens for about 1 out of 3 files (sometimes more). All the files are .mp4 format video files. Detacthing the Seagate drive from the Time Capsule and connecting it directly to the MacBook Air fixes the problem and allows the files to be read and played normally – this indicates the problem is with the Time Capsule, not the Segate drive.
Symptoms;
1) iTunes generates a file error with trying playing the video from iTunes,
2) selecting the file from Finder no longer generates a playable preview thumbnail as the Finder preview box remains blank (white),
3) attempting to play the file from Finder generates an unrecognisable file error in QuickTime,
4) connecting the external drive directly to the MacBook fixes the problem (the file can be read and played normally),
5) the files remain readable after reconnecting the external drive back to the Time Capsule, however the problem just reoccurs again later.
My normal use case is playing movies and TV programmes from iTunes to my television via Apple TV. Apple TV plays the video files over WiFi from the iTunes Library on my MacBook Air. The video files in my library are physically located on the Seagate external HDD attached to my Time Capsule.
I use a mid-2012 MacBook Air 13" running Mountain Lion 10.8.5. I have an 802.11ac (2 TB) Time Capsule (latest firmware 7.7.1) with a Seagate (1 TB) GoFlex drive attached (to the Time Capsule) via USB 2.0 (USB powered). The Seagate is my media drive and holds all my movies and TV programmes (all in .mp4 format). Both drives are Mac OS Extended (Journaled) with single partions. Time Capsule network is set to Bridged mode to resolve double NAT. I have an Airport Express extending the wireless netowrk to my MacBook Air. Prior to errors occuring, all files tested ok as follows; file plays ok locally on MacBook Air, files play ok from Finder after being moved to the Seagate, files play ok from iTunes library (pointing to Seagate).
Disk Utility verifies the Seagate drive has being OK. No other network issues.

Answer 1

Problem Solved!
The 1TB external HDD attached to my Time Capsule was divided into 2 equal partitions. The first partition used to be my Time Machine backup which I deleted and made available as free space. The second partition was the one I was copying to. It seems the Time Capsule has a problem with blank partitions on an external HDD. Once I repartioned the drive into a single 1TB partition, everything worked fine and my Time Capsule no longer crashes.