The reason this happens is because the CoInitFlags are not being set to COINIT_MULTITHREADED for an ISAPI dll (but, it is required!).

Add the following to the uses list of the main .dpr file:
ActiveX, ComObj
and have the following in the begin..end:
begin
CoInitFlags := COINIT_MULTITHREADED;
Application.Initialize;
...
CoInitFlags MUST be set before Applicaiton.Initialize.

Note: This is a setup issue, not a Delphi programming problem. Cause: This error happens because the anonymous user that IIS starts your process as does not have permission to write to some temp directories (Typically, for security reasons, it can't write to the directory where inetinfo.exe is located in your System32\inetsrv directory.)

Solution: The Paradox tables were not designed for multiple users hitting the database at the same time. The best solution is to use a SQL based database, such as Interbase, Oracle, or MS SQL Server.
If you must use Paradox and the BDE, then be sure to have a TSession on your WebDataModule. Set AutoSessionName to true. The key thing is to set the NetFileDir and PrivateDir to something that the anonymous IIS account can access. A good solution would be to set the NetFileDir to: C:\Temp\Net and the PrivateDir to: C:\Temp. The two cannot point to the same directory. In addition, it is best to uniquly set the PrivateDir for each webmodule, in the OnCreate event (typically, you will create a directory based on the current thread id, and set the PrivateDir to this). Otherwise, you may see each other's data from different threads. However, the NetDir MUST be shared across all processes and threads.

Next, you must give the IUSR_MACHINE_NAME and IWAM_MACHINE_NAME accounts full read and write permissions to the following directories:
1. The BDE directory
2. The base directory for your NetDir and PrivateDir
3. Your actual temp directory, probably C:\WINNT\Temp
4. Your directory that contains the database files
5. If all else fails, give read permissions to C:\WINNT, and then write permissions to C:\WINNT.

WebSnap Server-side Scripting

New help files

UsingWebSnap.pdf

A database-enabled Web user list

Getting started with WebSnap in Delphi 6 Enterprise

Loggin' in ain't hard to do

Paging Dr. WebSnap!

Persistent user sessions in WebSnap

Access rights in WebSnap

WebSnap is now in session

WebSnap: using Sessions and TStringsValuesList and server side includes (source code from corbin)

WebSnap: Guestbook source code (Kylix 2, but should work under Delphi 6)

The WebSnap Pack by Jimmy Tharpe provides the following free (postcard-ware) components to enhance WebSnap (see his website for more information):

• TDBWebUserList — A replacement for TWebUserList that validates users through a database.
• TudEndUserSessionAdapter — A replacement for TEndUserSessionAdapter that adds EndUser.DisplayName.
• TudLoginFormAdapter — A replacement for TLoginFormAdapter.
• TudStringsValuesList — A replacement for TStringsValuesList.