Dave, you shouldn't need flash player for this site, or at least to log in. It could be if you're not logged in you're seeing adverts, but they're not playing because your Flash isn't up to date - there has been an update recently. On the other hand it could be a malicious ad. Be cautious re. what Mike says.

If you get any more messages like that let me know, stating the time and date and what page you were trying to access.

The business about IE (and other browsers) forgetting your login happens when there's an IE update.