After upgrading one computer from NAV Classic 2010 to 2011 without any problems, I did the same with my older laptop .. with a 500MHz CPU, 574MB RAM and a 120GB HD. It worked fine too, but with one minor issue.
Here is the scenario: clicking on "Performance" in the Main screen I get a Performance screen without the customary "Home + Swoshed Arrow'" button (see attachment # 2b). Moreover, there is a blue border on top with the Windows style "X" (close window) to the right, rather than NAV's own style (see attachment # 1b).
PS: possibly unrelated, however, in Task Manager-Applications, when clicking on Performance, there are two instances of NAV running. On my 1st Classic upgrade I only have one instance running.
Other than that, everything works fine. Any ideas to correct this? I'm all ear. Best, CBA