Hi,
The following links detail some problems that can occur, especially at high load:-

1. Data loss WIN2K Sp4 http://support.microsoft.com/default.aspx?scid=kb;en-us;826482
2. Windows XP May Cause Extra SMB Notify Change Traffic http://support.microsoft.com/default.aspx?scid=kb;EN-US;330929
3. Disable RFCB Caching http://support.microsoft.com/default.aspx?scid=kb%3ben-us%3b126026

>Hi Neil.
>
>Yes caching is enabled on the server drives and I considered switching it off except for the fact that this setup has been running for a couple of years and this problem was rare. Lately it has become everyday common occurance.
>
>Also, the event log refers to an error on a seperate physical disk in the server holding non-VFP files which another non-VFP app is writing to (but which my program has called to RUN). But my app is losing access to a VFP dbf file on another physical disk on the same server. Something seems to have changed but not sure what.
>
>I think we will try (a) 100mb speed and (b) CAT6 cable. Then (c) switch off cache as a sequence of tests. Eliminating the most obvious suspects first.
>
>Thanks
>
>
>
>>Hi,
>>It looks like you have disk caching enabled, disable it in control panel.
>>
>>>>>Hi Al. Yes there is no switch between them and they are on a UPS. The other items I will need to check with the networks guy. Thanks. Wierd thing is that the problem seems to be getting worse. It used to happen occasionally, maybe once a month. Now it can happen even every day.
>>>>>
>>>>>I have noticed that a black exclamation icon appears in a yellow triangle in the system tray every time this happens. If you mouse over or click the icon it disappears without any tooltip or menu options.
>>>>
>>>>Jos,
>>>>
>>>>Did you Check Windows event log for additional info?
>>>
>>>Hi Sergey. Event log reports:
>>>
>>>error source=MrxSMB
>>>Delayed Write Failed. Windows was unable to save all the data for \Device\LanManRedirector. The data might be lost. This error may be caused by a failure in your computer hardware or network connection.
>>>
>>>However, the error detail in the subsequent popup event in the event viewer refers to another (non-VFP) file that my app is trying to write to on another disk on the server. So I am not sure if this is not actually a subsequent failure resulting from the first one or not. Also, this event does not always occur for every failure of my app.
>>>
>>>We are going to find a CAT6 cable as we were using a CAT5 cable. In the meantime we are going to run at 100mb to see if that makes a difference.
>>>
>>>Thanks.