problems after reinstalling vista

Hi all,
i have home premium and i had to wipe my hdd and start over. I reinstalled
vista with the same disk but have noticed some things not working.

the windows preview (thumbnails) on the task bar is greyed out and is no
longer projecting other open applications on the task bar as it once did.

The other issue is ie. i set the tab option to open all new windows in the
same window in a new tab. Yet it still opens new ie windows dispite the
settings.

I would be greatful for any suggestions.