Is the computer still blue screening? If so, check to make sure it's set to create a minidump file when it does.
Go to the Control Panel>System and Security, click System, then click Advanced system settings. In the new window, click the Advanced tab, and in the Startup and Recovery section, click Settings. Another window will open; in the Write Debugging Information drop-down menu, select small memory dump, and then click OK.
The next time it blue screens, go to the Minidump folder, copy the minidump file to the desktop, then upload it into the site I mentioned earlier, and copy and past the results in your next post.
Now would be a good time to ask about your system.
What version of Windows 7 do you have? Is it 32-bit or 64-bit? How much memory do you have installed? How large is the hard drive, and how full is it? The first set of questions can be answered by going to Control Panel>System and Security, and click System. As for the hard drive, go to the Start menu, click Computer, then click on the hard drive or drives.
Some other things you can try: http://windows.microsoft.com/en-us/windows/optimize-windows-better-performance#optimize-windows-better-performance=windows-7
Some are simple fixes, some are a bit more involved. For example, how often do you reboot? If the answer is not very often, you should consider shutting the system down when you don't plan on using it for long periods. Also have a look at the link. Start with deleting unused programs, limit how many programs run at startup if you don't need them to start automatically every time you log in, defrag the hard drive, run the disk cleanup utility (Internet cache and temp folders are good candidates for deletion), try turning off some visual effects, and run a full antivirus scan. If that doesn't make a difference, we can pick up from there.