@Bread: Thanks.
I checked the the source and the hosts file -- looks okay.
Did some other kind of 'e-snooping' too: I have this li'l app called
WinPatrol running all the time -- it detects changes made to various difficult-to-locate-but-crucial places including the registry and the hosts file. Plus I use
HijackThis to scan for unwanted changes. And [

] I also use
RegProt to prevent unwanted changes from happening. It's just that I like my personal computer to be personal.
The funny thing is this redirection happens
only for that particular site and no other sites.
Many thanks to Alex and Bread -- response was prompt and the service helpful. I'll post if any further weird stuff happens...