Thanks for the response, even though it is well over two years late!!!!
The problem seems to be one of file size and not duration. I *think* the problem occurs at the half a gigabyte threshold, though I have not tried to narrow it down exactly. I have one file that is less that half-a-gig and works with Slice but, due to a difference in bit rate, has a longer duration than a file that is over half-a-gig that does not work.
It is kind of you to point us to the free version of WavePad, but that is clearly not a useful substitute for Slice. In Slice I can request that a file be split into