When I lock up my monitor not hibernate just restart?Why?

Hi guy's i have 2 problem's but this to hang together.So i made reinstall Win Vista.And after when i want lock up my monitor is not  hibernate just restart.I download the Dell Recommended Vista Power Management Settings also.I sett the power manegment setting also, but nothing change.If i use Start Button and Hibernate it is work well.

The No.2 is also with battery support.I use Dell support batery mode, but when i change to Power safe mode or the other this Dell Support mode is lost and i have to install Dell Recommended Vista Power Management Settings again and after first time work well the hibernate .:S

Somebody Help pls...