I cannot open only orkut,way2sms. i can access the...

Question

we cannot open the few sites like orkut.way2sms,160by2.com.i can access the gmail only the problem is with orkut.some suggested me to re-install the operating system,i have done it for three but found no result.i formatted the system but not whole at a time,by copying a drive into another and formatting that drive like this all drives r formatted.whether i have to format the system whole at a time?