This might be a problem with the .dat cache file or it could be an issue with a corrupt configuration. Here are links to threads that discuss the steps needed to delete the .dat file and if that does not work to delete the config folder.
This should help you to get past these problems without having to re-install Dreamweaver.
cache file:
showthread.php?t=1589
corrupt configuration:
showpost.php?p=12293&postcount=2