ERROR Msg: No more internal file identifiers available

[TWmailrec]

I have been using FreeCommander XP 2015 build 685 32 bit Public which although slow to startup, works very well.

On occasions I get the ERROR Msg: No more internal file identifiers available; ( especially when run with /C parameter).

Since I needed a Portable version, I downloaded the donor 64 bit XP version.
The Readme file indicates that settings from previous XP 32 bit version can be imported.
When this was attempted, got the ERROR Msg: No more internal file identifiers available!

It is the same problem. Can anyone help with this? Has anybody seen this before?
Maybe an INI problem?
With my own program to quickly preset directories, I was forced to use 9.2 version