Unable to Login to MSN Live messenger

I'm unable to login to MSN Live Messenger & my Hotmail account using my HP
laptop when I switch on the wireless mode. However, if I connect the modem
directly to the laptop I'm able to Login into MSN Live Messenger as well as
check my mails in my hotmail account.

Also when my router is switched on my friend is able to access MSN Live
Msngr on his Laptop in the wireless mode.

I use Windows XP Service Pack 2. The Router is a NETGEAR WGR614 v6. The
Antivirus program I have is a Kaspersky 8.0.0.56

Kindly suggest the possible corrections in the settings that I need to carry
out.