Redmine

I am using Redmine 1.2.1.stable (MySQL) and all of a sudden I am unable to open one newly created issue.
All other issues (multiple hundreds) can be opened and everything else works fine.

The error message is 'Redmine 500 error', the server log says:
ActionView::TemplateError (OLE2 signature is invalid) on line #19 of vendor/plugins/redmine_msg_preview/app/views/issues/_msg_list.html.erb:
16: </tr></thead>
17: <tbody>
18: <% @issue.attachments.each do |att| >
19: < msg = Mapi::Msg.open att.diskfile >
20: <tr class="<= cycle("odd", "even") >">
21: <td><= lookup_property(msg, "SENDER") ></td>
22: <td><= lookup_property(msg, "SUBJECT") %></td>

vendor/plugins/redmine_msg_preview/app/views/issues/_msg_list.html.erb:19
    vendor/plugins/redmine_msg_preview/app/views/issues/_msg_list.html.erb:18
    lib/redmine/hook.rb:113:in `send'
    lib/redmine/hook.rb:113:in `view_issues_show_description_bottom'
    lib/redmine/hook.rb:63:in `send'
    lib/redmine/hook.rb:63:in `call_hook'
    lib/redmine/hook.rb:63:in `each'
    lib/redmine/hook.rb:63:in `call_hook'
    lib/redmine/hook.rb:60:in `tap'
    lib/redmine/hook.rb:60:in `call_hook'
    lib/redmine/hook.rb:144:in `call_hook'
    app/views/issues/show.rhtml:63:in `_run_rhtml_app47views47issues47show46rhtml'
    app/controllers/issues_controller.rb:122:in `show'
    app/controllers/issues_controller.rb:121:in `show'

Any ideas how to overcome this problem?