This is a bug in IE8 that Ancestry.com has not yet compensated for. If your ISP is AOL, microsoft has thrown up its hands and recommends uninstalling IE8. This unfortunately must be done with a great deal of caution.

If you go back to IE7, and it still does not work, it is quite likely that Vista's security settings are the culprit. Search this topic and the "improvements" message board for a post on how to adjust the security settings - sorry I can't tell you myself since I am not a Vista victim. The helpful user post was within the last month or six weeks.

Good luck,
Jade