Hello, I had difficulty with my laptop a couple of weeks ago to the point where I had to do a "refresh" on the laptop. I had installed Comodo Firewall, and after a time, my computers mouse would lag to the point of interoperability. When the computer would restart I would get a BSoD. After uninstalling Comodo and using the windows repair kit from Techspot, I managed to get the computer working, or so I thought. The SFC /scannow reported errors it could not fix. When Windows decided to update, I shut it down, and then turned it back on, only for windows to BSoD on startup, even before reaching safe mode. Windows could not launch from the hard drive for whatever reason. I could access it threw the command prompt in the windows RE, so I performed the repair commands that I could. I could not do a refresh using the one key recovery that came with my Lenovo Y510P, nor could I do so with the Windows 8.1 Pro installation disk. When I tried, they both stated the drive was locked. I was; however, able to do a refresh on windows using a USB recovery I made with another laptop. ~~ After doing the refresh and upgrading my laptop back to 8.1 pro I've been having some difficulties getting things to work as they should. Every so often my computer lags/stutters, and I see the working icon on the mouse. During this time, I get returned to the desktop no matter where I happen to be at the time. Out of curiosity, I ran a scan/log only of hijack this, and it showed a lot of missing files. I did not have it perform any actions. I have run Avast scans, and malware bytes scans, and neither have picked anything up. Since my laptop is 8.1 I cannot do a DDS scan, as it results in a "Cannot run in compatibility mode." If you could help me, I would greatly appreciate it.