Hi domagoj1x2,
I would suggest you to create a new power plan and customize its settings same as that of Dell power plan. Choose this new power plan as default plan and check what happens when yo restart or power on the system. You may refer to the link: http://bit.ly/14j4zrL.
You may update the system BIOS. Please refer to the link: http://dell.to/111hmLd.
Keep me posted with the results. I will be glad to assist further.