I've fixed a serious but obscure bug. Download ExcelDna-0.7.zip
When reading a string array as input parameter to a user-defined function, the marshaling sometimes caused an access violation by reading beyond the end of allocated memory. This would only happen when Excel is under some stress, as in real-time applications. In fixing this I have also cleaned up some of the marshaling code. A big thank you to Mark for helping me track this down :-)
So if you have had problems with your add-ins crashing under load, or in a real-time setting, please give it a try again. As always I'd love to hear your feedback about ExcelDna.