kimmydawn is right, it might be a "clear cache" thing.

When every you visit a web page (any web page) your browser stores the page information on your computer... so that when you visit that page again it will load faster. That stored information is called a cache.

The problem is sometimes the online page has changed, but when you visit your browser may load the page from memory instead of the internet site, not realizing the page has changed. You are therefore looking at the "old" version of the page.

Since you only added your sig recently, if you are having the problem when seeing older posts made before your sig was added, this is probably the problem.

You can make the new page load by clicking on the "refresh" button on your browser toolbar, then the sig should show. As kimmy said, if you clear your browser's cache, it will solve the problem for good (that is, for any previously stored paged... the cache will build itself up again as you web surf).

To clear your cache in Internet Explorer, click on Tools -> Internet Options and then on the "General" tab, where is reads "Temporary Internet Files," click "Delete Files".

In Firefox, click on Tools -> Options and then click on the "Privacy" pane. There you will see "Cache" and a button to clear it.

Other browsers may have similar tools. Don't delete Cookies, that is a different thing (anyone want to know while I'm on a roll? )

If you are on a slow internet connection, like dialup, the first time you visit your favorite websites they may take a little longer to load, especially if they have a lot of graphics. This will only happen on your first visit though, as the browser is going to "cache" all of that stuff fresh.