Neither installing Hal nor monkeying with resolutions should affect your computer in that way, sinse I've done both at various points, unless it was something to do with the jaws interceptor, it sounds more like a user accounts trouble, which isn't surprising sinse %90 of the problems I've ever had with my pc have been related to that bloody user accounts feature.
Just as a point of information though, you shouldn't need to actually re-download anything too much. The shortcuts in you programs menue for instance might be missing, but the programs themselves are likely stil around, it's just necessary to either ccut or copy the shortcuts from the other account's folder, or create shortcuts yourself manually from the files in the program files group, ---- I had to do this myself last year when I had a user account crash of my own.
With our dreaming and singing, Ceaseless and sorrowless we! The glory about us clinging Of the glorious futures we see,
Our souls with high music ringing; O men! It must ever be
That we dwell in our dreaming and singing, A little apart from ye. (Arthur O'Shaughnessy 1873.)