I reported this issue a year ago and I never figured it out. I'm still dealing with it today. It gives me some comfort knowing that I'm not the only one :)
In the latest version, when you open a chart it is "lccked" into the foreground on the screen and I'm unable to view any of the other windows on my PC until I close the chart window. I didn't have this problem on the previous version.
I've been using the TD Ameritrade version of QT (v4.0) for many years without issue but this morning the advertisement box is popping up insisting that I register and when I try to view historical charts I get a message that says I need to register QT in order to get more than 6 months of data. It didn't do this yesterday. Can you help?