This problem is typically caused by a setting in WordPerfect which controls the way document tabs are managed. However, this can also be caused by a corrupt document header.
To resolve this problem, follow the instructions listed below:
1. Go up to the Tools menu and select Settings. Click on the Convert button.
2. Remove the check mark from Treat Tabs Like MS Word.
3. Click on the Template button and select Yes to save standard template compatibility options.
4. Click on Ok then click on Close.
5. Close WordPerfect and reopen it.
If this does not resolve your problem, please refer to the following knowledge base article on WPLOOK: 207723-Repairing-WordPerfect-documents-using-WPLOOK