Q: What will happen when a part of a TrueCrypt volume becomes corrupted?A: In encrypted data, one corrupted bit usually corrupts the whole ciphertext block in which it occurred. The ciphertext block size used by TrueCrypt is 16 bytes (i.e., 128 bits). The mode of operation used by TrueCrypt ensures that if data corruption occurs within a block, the remaining blocks are not affected.Due to hardware or software errors/malfunctions, files stored on a TrueCrypt volume may become corrupted. Therefore, we strongly recommend that you backup all your important files regularly (this, of course, applies to any important data, not just to encrypted data stored on TrueCrypt volumes). If you do not have enough free space to backup all files, we highly recommend that you at least backup the volume header, which contains the master key (size of the backup file will be 1024 bytes). If a volume header is damaged, the volume is, in most cases, impossible to mount. To backup a volume header, click Select Device or Select File and select the volume. Then click Tools -> Backup Volume Header. To restore the header, follow the same steps except the last where you select Restore Volume Header.Q: What do I do when the encrypted filesystem on my TrueCrypt volume is corrupted?A: File system within a TrueCrypt volume may become corrupted in the same way as any normal unencrypted file system. When that happens, you can use filesystem repair tools supplied with your operating system to fix it. In Windows, it is the 'chkdsk' tool. TrueCrypt provides an easy way to use this tool on a TrueCrypt volume: First, make a backup copy of the TrueCrypt volume (because the 'chkdsk' tool might damage the filesystem even more) and then mount it. Right-click the mounted volume in the main TrueCrypt window (in the drive list) and from the context menu select 'Repair Filesystem'.