Outlook 2010 (64-bit) is my default mail-client (File > Options> General > bottom line; translated from Dutch, actual path could be slightly different in English). However, other programs complain there is no default mail-client selected. Adobe Photoshop Elements 8 refuses to send photos through Outlook because Outlook is not the default mail-client. Other programs complain as well and also refuse to start Outlook.
This must be a well-known problem, probably related to the 64-bit version of Outlook 2010. Is someone working on a solution?