Defraggler cashed on 2 TB drive

Windows 7 SP1 fully-patched, 64-bit.

Disk is 2 TB, 30% full.

Defrag takes place, apparently successfully, but on re-execution it crashes at 43%.

CHKDSK has been run on the offending disk, but the Defraggler crash still occurs.

Here's the brief crash info.

Can I get you any more information?

Problem signature:

Problem Event Name: BEX64

Application Name: Defraggler64.exe

Application Version: 2.6.0.328

Application Timestamp: 4e13ff88

Fault Module Name: Defraggler64.exe

Fault Module Version: 2.6.0.328

Fault Module Timestamp: 4e13ff88

Exception Offset: 00000000001c82c8

Exception Code: c000000d

Exception Data: 0000000000000000

OS Version: 6.1.7601.2.1.0.256.48

Locale ID: 2057

Additional Information 1: c6e0

Additional Information 2: c6e0e25c260d29f75ab13edbfaa32dea

Additional Information 3: 4006

Additional Information 4: 40061da3d83c2933fcd424e21ba4489f