I believe I'm 0/10 or so when seeking help on this boards for my site.
I went back through your posts and had a look, and oddly enough, every time you post about yet another problem with your sidebar (more then 8 issues with it over a period of more than two years), somebody else tells you the same thing: Make the site valid.
Have you considered that the reason you have problems every few months is because you have ignored every single piece of advice that we've ever given you? Did it never occur to you that we actually do know WTF we are talking about?
I will go elsewhere to find the solution for this problem, and I assure you it will not involve "fixing" 400 errors to get my sidebar aligned properly.
Nobody said it would. But it most certainly will involve looking at a huge haystack of errors when trying to find that needle.
Whereas if the page was valid, then the problem would be rather obvious and looking for it would not be necessary.
Also, read this: