There are probably only a small number of people using both Comstock and teh Advanced Search Sidebo, and even then, what is happening is likely to be dependent also upon which other sideboxes you are using and their order, so as you haven't provided a link to your site, only you can really see what's going on.

However, as a stab in the dark, the Advanced Search Sidebox has a structural problem that is visible on both the screenshot provided in the package and more specifically if you look at the code in the tpl_advanced_sidebox_sb.php file.

In the latter you will find that the filed set for the date from field is not closed. This may be having a knock on effect through the rest of each page.