Sudden increase in validate problems on Gamma-Ray Pulsar Binary Search

I have noticed a massive increase during the last 10 days or so in the number of validate problems for the Gamma-ray pulsar binary search #1 v1.05 (FGRPSSE) on i686-pc-linux-gnu.  These include "Completed, can't validate"; "Validate error" and "Completed, marked as invalid".

After running this search for many months on the same computer with a handful of such errors, I now find that 11 out of a total of 18 tasks have failed validation after running to completion (and at least one other task has been cancelled by the server).

I am running on a GenuineIntel Intel(R) Core(TM)2 Duo CPU E4500 @ 2.20GHz [Family 6 Model 15 Stepping 13] under Linux 4.4.0-81-generic (Ubuntu).   OK I know this is rather archaic hardware!!

Is there a reason for this sudden change in behaviour of the validator and are other users experiencing similar problems?

Alan Barnes