if you don't need ENCODE videos, DO NOT INSTALL THIS CODECPACK. it contains lot of cool codecs, which are easy to find, but in such compilation? noone is telling you "install professional", there is also "player edition" or "minimalist" one - just use those and it works fine. btw: it uses quicktime alternative, which is in trouble with itunes and quicktime also.
trouble with hangin' explorer? just don't use it. it is fast, but using key-commanded total commander you will be much faster - and see thumbnails too :)))