On a project (old VS 6 project upgraded minimally to work in VS 2005), I changed setting from "no clr support" to "clr support".
I got this warning now (that appears to from another DLL that is used in the project).
warning LNK4248: unresolved typeref token (01000015) for '_TREEITEM'; image may not run
I see this stems from a data type in the other DLL used. The data type is HTREEITEM which appears to come from commctrl.h.
Based on a little googling I did, I tried adding the comctl32.lib library. No luck.