If this is a network drive(or MSDE/SQL), you should probably setup a COM+
App for the vfp mtdll web service. This will allow you to use
impersonation. (It's amazing to me that this sort of stuff is not in any sort of vfp documentation!).
Here are some directions:

On Windows2000, go into Control Panel, Component Services: 
1.) Right click COM+ applications and select New.
2.) Go through the wizard, creating an Empty Application,
giving it a name/check server application, and selecting the appropriate
account to run under.
3.) After the Empty Application was created, right click on 'Components'
 under the newly created application.
4.) Select New/Component.
5.) The wizard starts and  select 'Import components that are already
registered.'
6.) Select your web service mtdll from the list and it add to this COM+ app.
7.) Right click on the COM+ application name (in this case, your web service
mtdll ) and select 'Start'. The COM+ icon is now revolving in the Components
pane.

>I am contstructing a Web Service and running into problems opening tables.
>
>When I run my Web Service class from VFP (i.e. load an instance of the class and make calls into it's member functions without going through the IIS manager) the program works correctly. I can tell it to open a file e.g. IF FILE(CcApplicationPath+"ARDATA\ARCUST01.DBF") USE (CcApplicationPath+"ARDATA\ARCUST01.DBF") IN 0. (Where CCApplication path is #defined perhaps, or read from a table perhaps).
>
>But that same IF statement when calling the Web Service via IIS returns .F. to the test for the file - it cannot "see" the DBF. I have tried substituting drive letter and directory (e.g. "S:\PRO65\") with the correct UNC name (e.g. "\\SERVER\PRO65\") but it makes no difference.
>
>I have given permissions to the file and to the parent directory to the Internet Guest Account IUSR_etc but this doesn't make any difference.
>
>Can anyone please let me know how an Internet user should find a file?
>
>Thanks
>Chris Palmer