The title describes the problem pretty well. I will use Sivaram's user page as an example, since his question and answer titles have a fair bit of LaTeX in them, but I am seeing this problem on all user pages. I've played around with this a bit, and I think the scope of the issue is this:
I start with a clean slate - I restart my browser and clear my cache. If I go to either
https://math.stackexchange.com/users/3302/sivaram
or
https://math.stackexchange.com/users/3302/sivaram#qpage_A-anpage_B-qsort_votes-ansort_votes
for any valid choice of $A,B\in\mathbb{N}$, all LaTeX renders exactly as it should.
However, as soon as I go to a user page and navigate the questions or answers using the page number buttons, the LaTeX stops rendering in the corresponding section, including if I press the back button. I have to refresh the page in order for it to work. For example, suppose I have my clean slate and go to https://math.stackexchange.com/users/3302/sivaram. I see what I'm supposed to:
and
When I click on the "2" button in the question section, taking me to
https://math.stackexchange.com/users/3302/sivaram#qpage_2-anpage_1-qsort_votes-ansort_votes
I see this:
Similarly, if I start with a clean slate, go to a user page, and click on the "2" button in the answer section, taking me to
https://math.stackexchange.com/users/3302/sivaram#qpage_1-anpage_2-qsort_votes-ansort_votes
I see this:
The really curious thing is the persistence of this effect. As I mentioned, as soon as I've pressed a page number in the question section, no LaTeX will render in the question section until I've refreshed the page (and sometimes not even until I've cleared my cache, but I've been unable to consistently reproduce that, so maybe I'm imagining it). I can press the back button, to the page I was on before when the LaTeX was rendering correctly, and it no longer will. I can press other page numbers in the question section, and LaTeX won't render on them either. If I've "broken" the LaTeX in the question section and start pressing page numbers in the answer section, the LaTeX in the question section stays broken (and now the LaTeX in the answer section will be broken too).
I'm using the latest version of Chrome (12.0.742.91) on 64-bit Windows 7, but I've noticed this problem for a long time (unfortunately I'm only now getting around to reporting it). I also experience exactly the same problem in Firefox 4.0.1.
EDIT: I've found that changing the sort criterion for questions or answers (i.e., recent, views, newest, votes) also precipitates the LaTeX problem.