Windows 7: All excel files opening in read only mode in Windows 7

Solution - Edit Message Method

If you put the email message into Edit mode you can edit the attachment and save changes back to the original attachment on the email message. You need to remember to save the attachment when closing AND save changes to the email message as the copy in the securetemp folder will be deleted when you close Outlook.
If you add the Edit Message button to the QAT or Ribbon, its very easy to get into Edit mode. To add the command to the QAT (or ribbon):

1. Open a message
2. Go to File, Options, then choose either Customize Ribbon or Quick Access Toolbar
3. Select All Commands from the Choose command dropdown
4. Click in the list of commands then press E on your keyboard to jump down to the Edit commands.
5. Find Edit Message and double click on it or use the Add button to add it to the QAT or Ribbon.
6. Click OK to return to the message.

The next time you need to edit an attachment and save the changes back to the message, open the email message, click the Edit Message button then open the attachment.
Remember: you need to save and close the attachment then save and close the email message for the edits to be saved. If you don't want changes saved (such as when rotating images), close without saving.

Solution - Disable Attachment Preview

You can make many attachments readable if you disable Attachment Preview. With this disabled you will lose the ability to view attachments in the Reading pane or open messages - you will need to double click to open them in their application.
Go to File tab, Options, Trust Center:

1. Click the Trust Center Settings button
2. Select Attachment Handling
3. Add a check to the "Turn off attachment preview" option.

Note: this disables preview for all attachments. If you like the attachment preview feature, use the Edit message method.

Solution - Images viewed with Windows Photo Viewer

A workaround for those using Photo Viewer exists: in Photo viewer, click on File, Properties, General tab then clear the Read only check. Repeat for each image.