Nope, no issues with multiple processors and VFP. You should compile to a MTDLL, though - why did you build as Single Threaded?
What files are you including with your Wise Install? For VFP 6, your .DLL app has got to be in the same directory as the runtime or the runtime has to be in the WINNT\System32 directory on the target machine.

We're doing something very similar - check out http://www.activevfp.com for resources and articles for using ASP/ASP.NET with VFP...

>Hi,
>
>We've developed a very simple COM Server DLL using Visual FoxPro 6 SP5.
>
>The DLL has been built as a Single Threaded COM Server.
>
>It works fine on both Windows NT and Windows 2000 on our test PCs. We install and register the DLL using a WISE script, and it is called from an ASP script.
>
>However, we tried installing it on one of our clients servers today. He is running NT Server 4 with Service Pack 5 installed. The DLL appears to be registered, but calling it from our ASP script gives a message that the object is not registered.
>
>We have tried manually registering the DLL using REGSVR32, which again gives the impression that the DLL has been registered. The ASP script continues to give the same message.
>
>We have tried unregistering, rebooting and registering the DLL again. No joy.
>
>The only difference we can see is that the client's server has two processors. Is there an issue with multiple processors and VFP applications/components ?
>
>Best.
>
>Matt.