Your system becomes unstable because of the malware programs running in the background. You identify these programs and kill them in the Task Manager but these programs will re-appear in the Task Manager after you reboot the system. This is because these programs will run again from the below mentioned registry keys:
To run only allowed programs, you need to modify the permissions on the Run and RunOnce registry keys.
- 1. Remove all the unwanted programs from Run and RunOnce registry keys using Registry Editor.
- 2. Remove any other account from the Security Tab except SYSTEM Account and grant this accound only the "Read Only" permission.
- 3. Reboot your system.