exit code 99 (0x63)

At this time I have 7 failed WU's, all with "client error" and "compute error".
If I look at the result files they all end with the same text :

===== WARNING: XLALComputeFaFb() should not be used with upsampled-SFTs!
XLAL Error - XLALComputeFaFb (ComputeFstat.c:390): Invalid argument
Level 0: $Id: HierarchicalSearch.c,v 1.164 2007/04/25 14:31:47 bema Exp $
Function call `COMPUTEFSTATFREQBAND ( &status, fstatVector.data + k, &thisPoint, stackMultiSFT.data[k], stackMultiNoiseWeights.data[k], stackMultiDetStates.data[k], &CFparams)' failed.
file HierarchicalSearch.c, line 1010
2007-05-07 08:30:33.1562 [normal]:
Level 1: $Id: ComputeFstat.c,v 1.67 2007/02/26 14:15:43 reinhard Exp $
2007-05-07 08:30:33.1562 [normal]: Status code -1: Recursive error
2007-05-07 08:30:33.1562 [normal]: function ComputeFStatFreqBand, file ComputeFstat.c, line 151
2007-05-07 08:30:33.1562 [normal]:
Level 2: $Id: ComputeFstat.c,v 1.67 2007/02/26 14:15:43 reinhard Exp $
2007-05-07 08:30:33.1562 [normal]: Status code 5: XLAL function call failed
2007-05-07 08:30:33.1562 [normal]: function ComputeFStat, file ComputeFstat.c, line 286
2007-05-07 08:30:33.1562 [CRITICAL]: BOINC_LAL_ErrHand(): now calling boinc_finish()

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Seems like a software fault of some kind, it only happens on my win/intel box, the win/amd box is doing fine.
So what is going wrong and is there something I can try.
The win/intel box is otherwise running smoothly.

Rob.