Cannot download Plugin for Word 2003

Hi, I'm using Word 2003 on Windows 7 and can't download the Plugin. Every time I try it, Mendeley tells me that Windows is running (even though it's not) and if I want Mendeley to try to close it. If I press yes the following answer comes up: Mendeley is waiting for Word and/or Outlook to stop running Do you want Mendeley to forcibly close Word and/or Outlook. When I press yes it tells me again that it's waiting for Word to be closed. Then I can only press cancel and Mendeley tells me that it's unable to install the Plugin. Can anybody help me and tell me what the problem might be? Thanks in advance! Martina