Uninstall the DM software - there is a RIM support notice entitled "How to do a clean uninstall" or something like that. Involved getting rid of the registry keys and any leftover files.
Try re-installing the latest version of DM (126.96.36.199) from the RIM web site. See if that helps.
I've seen this once or twice before (on Thinkpads also) and it just takes time... Sorry