Here are some things you can do to troubleshoot strange symbols in your document:

1. Check that you are using a supported document format and file type.
2. Check that encoding type is set properly.
3. Check that the file is in its original format.
4. Check that you are using the correct font.
5. Check the formatting.
6. Copy and paste from a plain text editor.
7. Run virus and spyware scans.
8. Check for system updates.