Is this the right place?..I need help with painting!..

[PinkChick]

all the walls in this house were painted in some sort of super shiny white paint that when ive painted over in other rooms(i use a matt paint) its gone 'crackly' like distressed look in area's..almost like the amtt has dried out what ever is underneath and its shrank???
Now ive been promising my dd id paint her room, but i really dont want to go to all the expense if its going to look rubbish..so what can i do to STOP the walls doing this????
Would sanding and undercoating help or would the under coat do the same?..i really dont like sheen walls, i think(when ive done them before) they always look patchy, so i want matt again?...any help much appreciated...

also is it just me or are the pages taking an age to load on here the last few days???

I think you are going to need to sand really well.

My guess is the matt paint has nothing to "adhere" too and is sort of shrinking.

yeah, thats what i thought..the first time i painted the living room the only way o could describe actually trying to paint it(my cousin PHSL laughing at me!) was as if you were trying to paint and ice pop!..it just seemed to be slipping off!?..so lots of sanding i guess..which means lots of dust!..will have to do it when the children are all at school and i have none coming and going through the day so i get cleaned up in time!