atop crashed with SIGSEGV in __libc_start_main()

I'd never seen this before. ATOP was dying before even getting started, according to GDB. Six hours later, it works fine.
At the time, I had some very memory- and disk-intensive processes running, moving 20GB files around.

ProblemType: Crash
DistroRelease: Ubuntu 11.04
Package: atop 1.26-0ubuntu1
ProcVersionSignature: Ubuntu 2.6.38-11.50-generic 2.6.38.8
Uname: Linux 2.6.38-11-generic x86_64
Architecture: amd64
CrashCounter: 1
Date: Sat Sep 24 03:56:43 2011
ExecutablePath: /usr/bin/atop
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Release amd64 (20110427.1)
ProcCmdline: atop
SegvAnalysis:
 Segfault happened at: 0x7f6dcf31b80f: rep stos %rax,%es:(%rdi)
 PC (0x7f6dcf31b80f) ok
 source "%rax" ok
 destination "%es:(%rdi)" (0x00000000) not located in a known VMA region (needed writable region)!
SegvReason: writing NULL VMA
Signal: 11
SourcePackage: atop
StacktraceTop:
 ?? () from /lib/x86_64-linux-gnu/libc.so.6
 ?? ()
 __libc_start_main () from /lib/x86_64-linux-gnu/libc.so.6
 ?? ()
 ?? ()
Title: atop crashed with SIGSEGV in __libc_start_main()
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm admin cdrom dialout disk lpadmin plugdev sambashare video