Not Playing Certain Music Files

I just got my 8GB+ and loaded it with 128Kbps wma & they sound terrible.

I then synced wav/Lossless files using Vista WiMP 11 & 2/3 of the songs do not play.

I re-encoded the same music using MP3 Pro 98Kbps & they sound Great…

I’m not looking forward to re-coding 786 Albumns & am wondering if I’m Missing something ???

                                                               Thanx for any help, Emily

I use xilisoft audio converter to convert my flacs to mp3, both flac and converted mp3s work in the sansa.  DBpoweramp also has a good converter too.

Thank You So much darling and I shall give it a try, Emily