i have a windows 7 home premium Lenovo 2days before i got the problem with a application and later i am reinstall my windows for making work fine for my application. now most of time my windows 7 goes hangs. can someone tell me why this happen. i can see last time my windows perform very well then now. now if i do something this make my computer hangs. can someone tell me how i can solve this issue.

You need to contact Lenovo Technical Support and use the warranty you paid Lenovo for. See info @ http://windows.microsoft.com/en-us/windows/help/contact-supportPlease remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.