I experienced the exact same issue, but managed to resolve yesterday doing the following:
1. Download current flash file from Adobe Website (choose the tar.gz for linux from the drop down option)
2. Open terminal and create a new folder: /usr/lib/adobe-flashplugin (you will need root privileges to create this folder)
sudo mkdir /usr/lib/adobe-flashplugin
3. Extract contents of downloaded tar.gz file (by default it may extract to the original file downloaded location)
4. Move / Copy the contents of the extracted file to the previously created adobe-flashplugin folder (again you will need root privileges)
5. Restart opera, everything worked fine for me and has done so for the last 24hrs.
Hope that helps.