Crash near the end of free space wipe on FAT32

[pcworld]

I'm using Eraser 6.1.0.2946 and get a crash near the end of a pseudorandom free space wipe on a 4.69 GiB FAT32 partition (2.11 GiB free) on Windows 7 32-bit.
I could reproduce the crash several times.
When I try to access the partition in Windows Explorer after Eraser has crashed, I get "X:\ is not accessible.\n\nAccess is denied." (drive letter is an example, line breaks escaped by me).
When I choose to close the program in the Windows crash report dialog, the partition becomes accessible again. The crash appears to happen at a stage where Eraser's temporary "fill-files" have already been deleted.

Here's the probably not very helpful Windows crash report:

Problem signature:
  Problem Event Name:	CLR20r3
  Problem Signature 01:	eraser.exe
  Problem Signature 02:	6.1.0.2946
  Problem Signature 03:	51f756e9
  Problem Signature 04:	mscorlib
  Problem Signature 05:	4.0.30319.17929
  Problem Signature 06:	4ffa561c
  Problem Signature 07:	251
  Problem Signature 08:	10
  Problem Signature 09:	System.ArgumentException
  OS Version:	6.1.7600.2.0.0.768.3
  Locale ID:	1031
  Additional Information 1:	0a9e
  Additional Information 2:	0a9e372d3b4ad19135b953a78882e789
  Additional Information 3:	0a9e
  Additional Information 4:	0a9e372d3b4ad19135b953a78882e789

Let me know how I can help you debug this if you intend to fix it.