It is one thing to install yourself as the default homepage quite another to have an ISP dialer launch spamvertizing sites like Bharatmatrimony.com every now and then on a customer's PC. I noticed it on a friend's PC and I suspect its the ISP dialer software provided by Sify. Does it happen to other Sify users as well ?.
PS: Yes bharatmatrimony.com is a spammer site. Proof I pasted a matrimonial ad in a newspaper with my e-mail ID and along with zillions of Un-solicited mail from marriage bureaus and like I also got an e-mail from Bharatmatrimony.com inviting me join their service and I decided not to renew their subscription anymore as I don't intend to support spamming operations however big they grow or however much VC/PE money they raise.