I have created two of my own functions that work nicely. But occasionally
they start to return #NAME? and this then filters through to every cell that
is dependent upon these functions. This seems to cut in when I sort the
sheet but is intermittent as sometimes the sort works OK???

In the past I have abandoned the current worksheet and gone back to an older
version where the functions worked. But his is not helping now, as the
error is also in the old version.

Anyone any ideas?