Here is a link without any of those options included:

https://www.democraticunderground.com/?com=latest_threads&page=2

If that link works, try just reselecting all of the default options for how the DU server shows the threads for you in the drop-down options at the top of the thread listing and using the normal page navigation features. (If a drop-down is already on the default, switch it to something else and then switch it back.)

If changing the options back to defaults doesn't fix it but that direct link worked, you could just change the page number in your browser address bar using the link above.

Edit to add:

Could you copy the link from your browser's address bar when you get that error? Maybe we can see if it is trying to pass invalid information.