There has been a very technical issues with the site recently. Here is a quick fix that usually works.
Type the thread title and thread content as "edit" then post it. After you have posted it and it works quickly edit the thread and copy/paste your originally planned title and contents in.
Reports about bad ads should include the following:
1. Location/Country
2. Device
3. Browser
4. Company/Product of ad
5. A screenshot if possible
6. Brief description of how the ad is a problem
7. Page/Pages affected8. Date and time of occurrence
Refer to the instructions for your device on how to take screenshots