After a gap of few weeks, today when I fired up Visual Studio 2010 Professional on my lappie, it showed me a dialog box, to obtain a new license key to extend the trial version.
As usual, I tried obtaining a new license online and pasted this key in the activation window and hit Activate button, but no luck, it keeps on throwing this error:
"The product key cannot be used to extend the use of this product"
Searched on the internet and came to this msdn forum http://social.msdn.microsoft.com/Forums/en-HK/vssetup/thread/518bc51d-56e1-4224-89d0-0645808d6b78 which eventually took me to this link, which proved very useful to troubleshoot the above error.
Tip: You can directly use the master key mentioned in the above link, it starts with YCFHQ..., just google it and you are good to go ;-)