"Our system has encountered a problem, please try again." when i try to create email template with using "Insert HTML" function

Steps to reproduced:

2. click on "New template" button

3. select "Contact" module and click "Next"

4. click on "Insert HTML / Plain Text" button

5. specify template name & topic, and then click on "Edit html" icon

6. paste html code and click Insert

Result: template was successfully displayed in preview area

7. click on "Save" button, select folder and then again click "Save"

Result: "Our system has encountered a problem, please try again."

This errors occurs only in my account. If i try to do this steps in another Zoho account - all will be ok.