Well while taking a look at the ace mega codecs pack it seems to be a lot of matrox codecs included in it.
A good advice would be to generally stay away from codec packs and go for FFDShow instead (much better IMO and less cluttering). Then it may need some extra's depending on videoformats etc. Like quicktime and realplayer formats, in that case there are great alternatives like RealAlternative and QuicktimeAlternative. All free and very useful IMO. Might be worth checking out..
Hope you can solve the problem!