I am using ASP.NET 2005 with QuickBooks 7 and QODBC 7 and I keep getting the error

[QODBC] QB Begin Session Failed. Error = 8004041c, An internal QuickBooks error occurred while trying to access the QuickBooks company data file.

The error happens on the line

sConnectString = "DSN=Quickbooks Data;OLE DB Services=-2;"

oConnection.Open(sConnectString)

I am using the vb sample code on the website. The vb sample app that came with QODBC works fine though.

Any suggestions of what I may be doing wrong?

Unattended mode (auto-login) needs to be setup. See: How do I setup QODBC to auto-login into QuickBooks and start it if it's not running? 

See also: How can I see QuickBooks data in a Internet Explorer Browser using Windows XP? 

The VB Demo works fine in unattended mode. My ASP.NET app now just hangs and won't return an error or anything. Here is my sample test code.

sConnectString = "DSN=QuickBooks Data;OLE DB Services=-2;"
sSQL = "SELECT FullName FROM Customers"
oConnection = New ADODB.Connection
oRecordset = New ADODB.Recordset
oConnection.Open(sConnectString)

oRecordset.Open(sSQL, oConnection, CursorTypeEnum.adOpenStatic, LockTypeEnum.adLockOptimistic)

Do While (Not oRecordset.EOF) 
      lblCustomer.Text = lblCustomer.Text & oRecordset.Fields("Name").Value & "<br>" 
      oRecordset.MoveNext()
Loop  

oRecordset.Close()
oRecordset = Nothing
oConnection.Close()
oConnection = Nothing

Well I'm guessing that your ASP.NET app is running through a Windows service. Have you setup the QODBC DCOM Servers or the Remote Connector? See: How can I see QuickBooks data in a Internet Explorer Browser using Windows XP?