Hi Amit Rajemahadik,
Even i am also facing the same issue for SMP Mobile SDK 3.0 Win (zip, appr. 872 MB)
I have tried it in Google chrome (version 32.0 ), IE (version 11.0) , Firefox (version 26.0) on windows 7 and XP (being on corporate network and public network)
In few seconds this zip file gets downloaded and when i extracted, it says
So i contacted devcenter@sap.com
they said they were having problems with the download server for past several weeks. It would cut of transmission of files and not send the complete file. They claim the problem has been fixed but still i am facing the same issue.
Why don't you contact devcenter@sap.com also with proper explanation and i hope this issue will get sorted out immediately.
Rgrds,
Jitendra