Hello ExcelDna Users,
A serious bug in the ExcelDna multithreaded support for Excel 2007 has been reported.
High-performance functions that are declared as IsThreadSafe=true, running under Excel 2007, and running on multi-core machines might return incorrect results. In some cases the function might return a result from a different thread, hence from a different calculation.
I'm currently looking at the problem and should be able to release a fix by Monday. The bug is in the marshaling code, where I misunderstood how the custom marshaling interacts with the native stub that the runtime generates.
This does not affect ExcelDna based add-ins running under older version of Excel, or functions that are not explicitly marked as IsThreadSafe=true.
I am very sorry for any trouble or inconvenience this might cause.