well what i suggest is going into your IWD directory [in my case: C:\Program Files\Icewind Dale\mpsave] copy all of those files to a second source. or better yet, make a zip file with them in it. and you will need to reinstall IWD:HoW. but if you reinstall you will uninstall IWD too. so go through Control Panel, Add/Remove Programs, and uninstall IWD:HoW then if applicable uninstall IWD. open C:\Program Files\ and delete the IWD folder. then install IWD then install IWD:HoW. and copy your backup character saves back into the mpsave directory.
hope this helps
hope this helps