Windows Media Player on Vista

[#1]

I have some music video tracks that I play quite often on Window Media Player using Vista....
I like WMP because I can save the Playlist, and all the settings I used to play that particular playlist are also saved...
Lately I have noticed that the sound level varies quite regularly and quickly from soft to loud, (not excessive,loud or soft) but enough to spoil the overall enjoyment....
it is a bit like a ship rolling from side to side in a rough sea.... despite the rolling to and fro, the ship eventually makes its destination, but the passengers have not totally enjoyed the journey... !
has anyone had this problem, and how did you solve it?
is it possible to uninstall WMP in Vista, and re-install it from a download?
as a point of test.... I have played the same .wmv file on VLC player, and it is perfect..... so I am assuming it is a problem with WMP rather than the conversion of the file from mp4 (download from the web) to .wmv

[#2]

not noticed this on wmp11. i only really watch avi files on it and mostly use nero vision for movies.
have you tried the quiet mode settings and srs wow ect to see if they make a diffrence

[#3]

Yes, I tried them,  (actually had been using them, before this happened) and have turned them off, as I thought that was causing the problem.... All settings, (apart from my preferences on the graphic equalizer) have been disabled, so it is running in "basic" settings mode...