|Did you run a virus scan? Common when infected to have the infection restrict access to files that allow their removal. |
If you performed a system restore to an earlier date and that solved the problem you may need to remove all restore points.
To remove ALL restore points you turn off system restore and then turn back on. Create a restore point at that time.
Don't do that until you are sure the system is running fine. No way to recover those removed restore points.