Since updating to IE9 a few months ago, I've noticed that sometimes when using Ctrl-\ to fill out a site, it will pop up the 1Password window with the current logon greyed out and saying there are no logons for that site, even though there are. This can happen on extremely common sites like amazon.co.uk that are definitely in the list. Once it begins happening (from memory) I won't be able to auto-fill any sites.
If I then use the drop-down to manually "select and go", it will give a pop-up saying there may be a problem with explorer and to restart it. When I restart explorer, Ctrl-\ works just fine. Or I can just open up 1Password seperately, and cut and paste the password out until I'm ready to restart explorer later.
I wouldn't normally complain, but it happens a few times a day, and has become a little grating
Maybe I can help you find the cause of the problem? Like all great problems though, it seems to be fairly random... I can't exactly make it happen. I usually only have a few (1 or 2) IE9 windows open at once, and a few tabs on each, and I only logon to a couple sites here and there. I usually shut IE9 down at the end of the day but sometimes it's running overnight. I don't have any other IE9 problems, and I didn't have any problem at all with IE8.
IE 9.0.8112.16421; no special addons (basic java, shockwave flash/activex, adbove pdf link helper, then the microsoft addons for live, media player, silverlight, and research).
1Password 188.8.131.52; 197 logins synched over dropbox w/ mac, iphone, ipad versions.
Vista 32-bit Service Pack 2