The crash consistently repros for me, shortly after navigating to http://www.dinorpg.com/clan/7 on safari 3.1 and then mousing over the "ENTRER" button in the top right
Created attachment 20421 [details] Crash after navigating to http://www.dinorpg.com/clan/7 and mousing into the page Windows XP
Crashes Mac Safari 3.1 for me, too, but a current debug build works fine.
Created attachment 20422 [details] Crash after navigating to http://www.dinorpg.com/clan/7 and mousing into the page Windows XP
Comment on attachment 20422 [details] Crash after navigating to http://www.dinorpg.com/clan/7 and mousing into the page accidentally reposted the dump
Created attachment 20441 [details] Reproducible test case -- mouse over the buttons
It looks like this bug is a dupe of rdar://problem/5729674 which was fixed: http://trac.webkit.org/projects/webkit/changeset/30414
This was fixed in trunk but the fix was not included in Safari 3.1. See linked tickets.