Helena,
I looked at Tools > Current Project Properties > Open Applications > General and NativeFirefoxObject was already above NativeUIAObject and NativeMSAAObject. Not sure how else do i make Testcomplete to use Web identification instead of UI Automation and MSAA identification.
I had the latest Firefox support patches installed, but that made Testcomplete crash very often. I had submitted all the data to the support team for that issue, it was stopping me from running my tests so I had to uninstall the latest firefox support patches and latest versions of Firefox (10) using FF8 right now.