Blast+ Error: Sequence Not Returned

I'm getting an error when running blastn against the nt database:

Error: (117.2) CThread::Wrapper: CThread::Main() failed
NCBI C++ Exception:
     Error: (CSeqDBException::eArgErr) Sequence not returned.

The actual command line is

/export/ocbn/ncbi/blast/bin/blastn -query orf02468.fas -db /export/ocbn/ncbi/nt/nt -num_threads 64

This is run on a SUN SPARC box (Victoria Fall) with 16 cores and 128 threads.

Any help, appreciated.