Starting yesterday, any site that uses Flash will not open the Windows "open file" window. I first noticed this on Photobucket, when trying to upload files. I click on the "upload a file" button, which is its own little Flash frame, and nothing happens. I've since had the same issue on imgur and Gmail, both of which use the same technique of embedding a Flash frame into a webpage. I've found workarounds on all three sites, but this is very annoying. I've been told that it might be an issue caused by ad block, but it keeps happening even when I pause ad block. When I use Firefox, I do not have this issue. Only Chrome.
I am using Windows 7, Chrome 16, Flash 11.1.
Here's a post on the Photobucket blog indicating that the same issue existed in February of this year and was caused by a Flash update.