I have caught the similar (or even the same) problem once with
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Linux version 3.0.0-12-generic (buildd@vernadsky) (gcc version 4.6.1 (Ubuntu/Linaro 4.6.1-9ubuntu3) ) #20-Ubuntu SMP Fri Oct 7 14:50:42 UTC 2011 (Ubuntu 3.0.0-12.20-generic 3.0.4)
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I have caught the similar (or even the same) problem once with _______ _______ _______ _______ _______ _______ ____ _______ _______ _______ _______ _______ _______ __
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Linux version 3.0.0-12-generic (buildd@vernadsky) (gcc version 4.6.1 (Ubuntu/Linaro 4.6.1-9ubuntu3) ) #20-Ubuntu SMP Fri Oct 7 14:50:42 UTC 2011 (Ubuntu 3.0.0-12.20-generic 3.0.4)
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At that moment the USB flash disk was removed.
log attached