Have you tried the following Package.INI setting in your Corel Draw application:
ChildProcessEnvironmentDefault=External
How about this information from page 90 of the ThinApp 4.7 manual PDF:
Viewing Attachments in Microsoft Outlook
Microsoft Outlook creates a default directory to store attachments when you open an attachment for viewing.
The typical location is C:\Documents and Settings\<user_name>\Local Settings\Temp\Temporary Internet Files\OLK<xxxx>. The last xxxx is replaced by a random entry. You can view attachments when the viewing application runs in the same virtual sandbox as Microsoft Outlook. External applications might not be able to find the file to display because Microsoft Outlook stores the file in the sandbox. You must use the Merged isolation mode for the directory that stores the attachments.
Set up Merged isolation mode to view Microsoft Outlook attachments
1. Add a value to the HKEY_CURRENT_USER.txt file that sets the name of the attachment directory:
isolation_full HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Outlook\Security
Value=OutlookSecureTempFolder
REG_SZ~%Profile%\Local Settings\OutlookTempxxxx#2300
In this example, 11.0 in the key name is for Microsoft Outlook 2003.