There are numerous things that could cause this... take a look first at virus scanners. If you are running virus scanners on the servers, try excluding the working directories of your app (data,temp,etc).

In the past, this error was linked to Novell client access quite a bit.

>We are maintaining a Web application developed in ASP 2.0 and backend being Visual FoxPro 8. We create/build Web DLLs in Visual FoxPro 6 SP5 and using as COM+ Components and they are used to act as a bridge to the web application and the backend tables. We have web application in one server and the data in another server. We do have batch programs written in VFP 8.0 running in schedule tasks from data server which acces the data.
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>We are getting the errors "Error 1104: Error reading file" rarely from the web DLLs and are solved automatically. Please let me know the cause and the resolution for the same.