OK i found a solution..about IE7 markers problems
The prob is :
Marker Title
-Special caracter not reconized on IE7 like "
?" for eg.
-Edit the user who put a special caracter on "Marker title" and replace it with a normal one (for eg "
a" instead"
?")
so you can see markers on IE.
If have try all solutions posted above and the only one who work is this one..
Of course u can add a warning about that for prevent users on your template.
Waiting on a fix - thx for all
note : soz for my english coz i'm french noob

and use Firefox ^^