The freshness vs banked issue is more relevant if we are discussing positive findings with known risk of contamination. Banked samples would seem to have more contamination risk. However, with negative findings, what is the risk of contamination? A contaminant can not cause a negative, to my knowledge anyway. Besides that point, the real challenge to this report is that these were cell lines, which generally means they have been maintained for a long time, perhaps incubated, fed, worked on, etc. That increases risk of contamination and MuLV viruses are common contaminants, and a lab using MuLV species (such as for positive controls in an XMRV study) is more at risk. Even if they have never used MuLV before, there is contamination risk as MuLV is sometimes found to contaminate commercial reagents. However, if you want my complaint, here it is. False positive/negative risks do vary by type of PCR test, I looked into that a year ago, if memory serves, real-time PCR (most of the 0/0 studies) has higher risk of false negative, and traditional PCR (WPI) has higher risk of false positive, in some documented cases. So there is a possibility that any lab on both sides could be wrong. This is early stage research and we are waiting for a preponderance of evidence that will be accepted by the scientific community. My other complaint is that the CFS world has latched on to XMRV as if it is the answer and that is most definitely not proven at this point. I think we need a more balanced view, look at strengths and weakness on both sides.