First, I don't really see how using StlPort makes you have to link against the dll version of OIS as opposed to the static lib. If you are using StlPort in your app, however, you will need to build OIS with StlPort (and, if you are building your app in debug and using Ogre you probably want to define _STLP_DEBUG in debug build - for all projrects).
You don't mention what compiler you are using. Do you really need stlport? Sounds like a memory corruption problem possibly, though I need more information.