>Hi Nick/Claude
>
>>Matt, in addition to unregistering, make sure that there are no registry entries (related to the DLL) left, before you try to register it again.
>>
>>Also, single-treaded DLLs are almost useless, as you cannot even instantiate it second time within the same application without releasing the existing instance first. If you create it for Web application then (depending on purpose) you pobably should use MTDLL under MTS, as Claude says.
>
>We have the runtime libraries in the same directory as our DLL.

I would rather place them under WINNT\System32

>
>I'm not sure how we would find registry entries relating to the DLL - do we just search on the name of the DLL and the name of the class ?

Yes, you can do it manually through REGEDIT, but it is tedious. Use a utility like COM Explorer from http://www4developers.com or a similar one. You will be able to wipe them out in one click.

>
>I'll take your advice re. using MTDLL, but how do we use it under MTS ? Is MTS a standard component of a Windows NT installation ?

MS says: "MTS 2.0 is included as a feature of Microsoft Windows NT Server, Enterprise Edition 4.0, Microsoft Windows NT Server, Standard Edition 4.0, Windows NT Workstation 4.0, and Windows 95 operating systems. In addition, existing licensees of these operating system platforms can obtain MTS 2.0 through the Windows NT 4.0 Option Pack."

If you don't have it, you can download its with Option Pack from http://www.microsoft.com/ntserver/nts/downloads/recommended/NT4OptPk/default.asp

>Also, the single threaded DLL appears to work ok on our test NT and 2000 servers - we have even tested on a freshly installed server with no problems.

Was it just one instance? What about multiple users hitting it at the same time?