>I have occasional errors that I cannot understand when using SQL INSERT. This happens when I run the code in a DLL and the Error message says something about "UI not allowed", but the line of code is an Insert command that sometimes inserts a huge memo field.
>I am wondering if it is possible that another user is querying/updating this record before the memo field is fully written.
>Is there a way to LOCK the record while it is being inserted?

While I'm no expert at DLLs, and based on my little knowledge, your problem is not directly linked to the INSERT command, but rather that your DLL is trying to display something, maybe an error message. That is not acceptable in a DLL.

First, I'd try doing the same INSERT in VFP's command line, if possible, and see what happens. On you could try using an ON ERROR command to write errors to a file. Could you post the line of code that is causing the error?

As for locking, it depends on your back-end. If you are using DBFs, you can use RLOCK(). SQLServer has it's equivalent although I don't remember off the top of my head. But, like I said, I don't think your error is related to that. Plus, as far as I know, the record is automagically locked when you're updating.