The fact that things work in Safe mode suggests that the problem is with the registry, with Normal.dotm, or with an add-in. Try deleting the Data key or the whole Word key in the registry, then try renaming Normal.dotm, and finally troubleshoot add-ins, as discussed in the article at
http://support.microsoft.com/kb/921541/en-us/ (How to troubleshoot problems that occur when you start or use Word 2010, Word 2007, Word 2003, or Word 2002).