>From time to time IE7 has weird behavior as a new tab is opened either through clicking on it or by asking for a link to be openned in new tab: specifically the menu disappears in the new page. By right clicking in one of the toolbars sometimes the "Menu Bar" option is disabled. At other times is is enabled and checked. At those times by unchecking and then rechecking the option the menu reappears.
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>I worry that this may be be a sign of some "malicious software". Any ideas?
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IE7 is malicious software. I had to fight to keep it off my PCs.