Pattern to record: Available capacity falls sharply although visible folders are small.

Identify the storage layer

This guide applies to an NTFS-formatted Windows volume. Confirm the file system and physical-drive condition before interpreting directory, permission or repair messages; logical repair cannot make failing media reliable. A configured shadow-copy or backup feature can retain data outside the visible folders; first identify the actual provider rather than assuming every NTFS volume has snapshots.

Protect data before repair

Avoid writing repairs to the only copy of important data. Deleting snapshots can remove a recovery point.

Evidence to check on the protected copy

1. Image or clone unstable media first, then examine file-system and storage health separately.
2. Enumerate supported snapshots and backup state before deleting anything.

Recovery and verification

If the checks support this cause, remove only confirmed unnecessary snapshots and correct backup behaviour. Verification should cover verified startup, file permissions, large file reads, updates and backup.

For an assessment of your Windows computer, contact AEPC in Burswood or call 027 908 8880. Provide the model and the conditions that reproduce this problem. Workshop visits are by appointment.