Problem scanning in safe mode

Hi there,
hope someone can help me. Anti Virus System Pro attacked my laptop. I managed to download the Malwarebytes Anti-Malware in safe mode. I had to stay in safe mode as the virus will not let me open anything otherwise. The only problem is once it starts scanning my computer shuts down. What am I doing wrong??
Thanks in advance.
Annie

Please download the current version of HijackThis from HERE

• Double click and run the installer.
  
• It will install to C:\Program Files\Trend Micro\HijackThis\hijackthis.exe
  
• After installing, you should get the user agreement, press accept and Hijack This will run.
  
• Select Do a system scan and save a log file. This will open a notepad file of everything Hijack This found, copy and paste it back here.
  

Thanks so much for responding so quickly. I actually think I am all set. I turned my comp off for a couple of hours and tried it again and it worked fine, managed to scan without it shutting down.
Thanks a bunch!