This happened just recently to a sql server user - just reinstall the mdac and let me know if that clears up your problem. From what I have seen in the past - this just means that what you are referencing was not registered properly. You could track down the component and register is manually but reinstalling is much easier.
The Oracle Provider OLE DB 18.104.22.168.0 - was that provided in the mdac installation or a separate installation ? If it was separate, who supplied the driver ? Also, look in your registry to see which driver you are using for this driver - you may have to copy the key that has this reference to find the actual dll.
The default OLEDB values are located in the registry at: \\HKEY_LOCAL_MACHINE\SOFTWARE\ORACLE\OLEDB . Check the values for missing values.
You can try to get better error messages from your code. Since you are using Visual Basic, the error text can be returned as well using the Error collections object of the ADO model. If you have the on-line documentation see the "Oracle Provider for OLE DB User's Guide " for some clues.
I had a problem with CLOB fields, and this was my solution
install the file ODAC:
oracle dot com/technology/software/tech/dotnet/utilsoft.html
Set Conn = Server.CreateObject("ADODB.Connection")
'OraOLEDB.Oracle only works after ODAC install
DSNTest="Provider=OraOLEDB.Oracle;Password=xxxx;Us er ID=uuuu;Data Source=dddd"
rs.Open "Select * from tab_with_clob where rownum=1", Conn
for each x in rs.fields
response.write(" = ")