I looked at the site in Firefox, IE11, chrome, Safari, and Opera - the site looked the same. Who is the event director that's out out place at times and what browser are those people who see it off using?
Looking at your code, I have the following comments:
The h tags are meant to be used for titles in order of relevance. so your most important title (often the page name) would be h1, secondary titles would be h2, etc. You're not using these tags semantically correct, however, that would not explain your centering issue.
I also notice that in your listing of names, on several spots you put a space before the comma. This has nothing to do with webdesign, but if you want to write correctly, it should be NameCommaSpaceName - not NameSpaceCommaSpaceName.
You're using the <center> tag which is deprecated, and there is an empty abbr tag which serves no purpose.
You say you have the p centered in your CSS - but there is no <p> in your html.