Hello alexander and welcome to Seven Forums.
Are you able to access Advanced Boot Options? If yes, select Safe Mode with Networking. Advanced Boot Options
Run a full scan with your installed antivirus suite. Make sure you update the data base before running the scan. Then download, install, update, and run another free on-demand scanner called Malwarebytes
. (No antivirus program is 100% effective 100% of the time so having a second tool is always a good idea.) If the scans want you to restart the netbook, make sure you come back into Safe Mode with Networking.
After running the scans I'd suggest checking your system files to make sure they haven't been damaged or corrupted. Run a System File Checker scan from within Safe Mode at an elevated command prompt (Option Two, this tutorial.) If problems are noted run the scan 3 times (in Safe Mode) rebooting in between each scan. SFC /SCANNOW Command - System File Checker
After that see if you can do a Startup Repair, also from the Advanced Boot Options menu. Since you've got a netbook I'm guessing you don't have an optical drive to play CDs or DVDs and you probably didn't get any installation media from the manufacturer. This tutorial will show how to do a startup repair if you have a hidden recovery partition on the hard drive. You should run this at least three time rebooting in between each scan. If your computer didn't come with a hidden recovery partition please advise. There are some other things you can try. System Recovery Options