A form (the first and main form for the app) works most of the time but fails now and again with the following (standalone) behaviour.

It is opening a bunch of files in the dataenvironment.
It gets to Cursor 18 and falls over with the error message "Index (blah) does not exist"

If I suspend at that point, the current work area is not cursor 18, it's cursor 1, so when the dataenv init method fires for cursor 18 "Set order to (blah)" naturally enough the index doesn't exist. If I manually force it to "select (cursor 18)", it can then, of course, resume quite happily.

This is bizarre for a number of reasons.

1 I've never seen it before
2 If it happens at all, why doesn't it happen every time.
3 It happens with multiple versions of the data including newly created virgin sets (so its not a simple index or data corruption problem)
4 The files can't be open elsewhere as this a standalone app and this behaviour always (and only) occurs on opening up the application.

Suggestions?