Connection is good but it wont let me connect

Hello,
Alright my mom had the dsl cd installed on ur comp. but ur comp all of a sudden stopped working. When hers stopped working the internet stopped working as good. I still can get on but it is slow and it sometimes doesnt work at all even tho the signal says excellent all the time. any way i can get help or the neways i can get the dsl cd somehow. Does neone no if the cd is the problem or not please help thanks