You can fix this problem by doing a Software Update.

1. Go to your Chat Monitor settings, either by clicking on the icon (Visible Mode), or using your Hot Key combination (Stealth Mode).
2. Click on the "File" menu and go to "Update Software"
3. Go through the Update Wizard

The existing emails will not change but future ones will be recorded properly. If you see "This message may contain unsupported text", this is the Direct Connect Feature of AIM and is usually a file or a picture. It uses binary characters which cannot be recorded.