Your browser probably screwed up caching.
Here's your access log for the past few days:
[03/Feb/2007:10:38:21 -0600] "GET /forum/Smileys/classic/shocked.gif HTTP/1.1" 200 1481
[03/Feb/2007:12:44:09 -0600] "GET /forum/Smileys/classic/shocked.gif HTTP/1.1" 200 1481
[03/Feb/2007:17:37:27 -0600] "GET /forum/Smileys/classic/shocked.gif HTTP/1.1" 200 1481
[04/Feb/2007:03:54:14 -0600] "GET /forum/Smileys/classic/shocked.gif HTTP/1.1" 200 1481
[04/Feb/2007:18:31:36 -0600] "GET /forum/Smileys/classic/shocked.gif HTTP/1.1" 200 1481
[06/Feb/2007:23:06:41 -0600] "GET /forum/Smileys/classic/shocked.gif HTTP/1.1" 200 1481
[07/Feb/2007:08:19:36 -0600] "GET /forum/Smileys/classic/shocked.gif HTTP/1.1" 200 1481
[07/Feb/2007:19:37:10 -0600] "GET /forum/Smileys/classic/shocked.gif HTTP/1.1" 200 1481
[07/Feb/2007:23:01:36 -0600] "GET /forum/Smileys/classic/shocked.gif HTTP/1.1" 200 1481
[08/Feb/2007:12:48:04 -0600] "GET /forum/Smileys/classic/shocked.gif HTTP/1.1" 200 1481
[10/Feb/2007:13:08:40 -0600] "GET /forum/Smileys/classic/shocked.gif HTTP/1.1" 200 1481
[11/Feb/2007:11:56:28 -0600] "GET /forum/Smileys/classic/shocked.gif HTTP/1.1" 304 -
[11/Feb/2007:13:08:00 -0600] "GET /forum/Smileys/classic/shocked.gif HTTP/1.1" 200 1481
The status code is the second-last variable on the line. Where you see "200", that means "ok, it was returned". However, where you see "304", that means "Not modified, use what you cached last time".
Apparently at 11:56 this morning, the server told you to use the cached version. That's probably when you got the broken one. Then at 13:08, it sent you a fresh copy, so now it's good.
So it's pretty obvious that it's a caching problem. Weird that that would happen, though.
