The INSERT INTO command briefly locks the table header. If 2 inserts happen at the same time, you'll get error 108. Also some commands, like DELETE FOR/WHILE, REPLACE FOR/WHILE look the table whick could cause a similar result.

>
>Error 108: You have attempted a USE, DELETE, or RENAME command on a file that is being used by another user on a network
>
>I get this error and I don't see how it would happen based on this scenario. The error does not happen too often - maybe five times a year.
>
>

>Use MyTable IN 0 alias MyTable again shared && Was able to open the file successfully.
>Insert into MyTable (fld1, fld2) Values (NextId(), "Hello World") && Error 108 happens!!!
>
>function NextId()
>local nNextId
>nNextId = -1
>cAlias=alias()
>use MyId in 0 alias MyId again shared
>go top
>if rlock()
>  replace nextid with nextid + 1
>  nNextId = nextid
>  unlock
>endif
>use in select('MyId')
>select (cAlias)
>return nNextId
>
>Environment:
>1. MyApp.exe runs on several MyAppServers. There are at least 25 instances of MyApp.exe running.
>2. Data resides on MyDataServer.
>3. At any given second, there can be at least 5 queries, updates or inserts (any or all) against MyTable.
>4. SET REPROCESS TO 2
>

>
>What preventive code should I put in - probably before the INSERT statement? I don't want to use the AutoInc functionality as the tables are before that version of VFP.