Hello Risha,
A concern is that the changes you all are making are possibly worsening the situation. I will provide some initial ideas you can try, and then see if you can get some scan log info to post back here for review.
First just see if you can stop the shutdowns from occurring.
1 - Before it shuts down, go to Start - Run, type in
shutdown -a (and OK).
2 - Right-click My Computer, and then click Properties.
3 - Click the Advanced tab.
4 - Under Startup and Recovery, click Settings to open the Startup and Recovery dialog box.
5 - Clear the Automatically restart check box, and click OK the necessary number of times.
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Try working in Safe Mode, or Safe Mode with Networking. At startup tap the F8 key about once per half-second then select Safe Mode from the menu.
To keep them from interfering with the repairs, be sure to temporarily disable all antivirus/anti-spyware softwares while these steps are being completed. This can usually be done through right clicking the software's Taskbar icons, or accessing each software through Start - Programs.
Download
RSIT (random's system information tool) from
here to your desktop, then click on the
RSIT.exe to start the scan.
If necessary allow it to locate or download a copy of HijackThis as needed.
Once the scan completes a textbox will open - copy/paste those contents here for review please. The log can also be found at C:\rsit\log.txt.
RSIT will also create a second log, info.txt, which will be minimized to your taskbar. Post that here as well please (it will also be stored at C:\rsit\info.txt).
You can break logs into parts and use separate posts here when replying and posting the log files, if needed.