Safe mode

I have 2 Inteva PC’s they are part of a network segment of 20 pc’s these 2 have Windows 98 and Office 2000 installed on them.When they are shut down with Re-star or Re-set they try to re boot on safe mode and are lucky if they come up at all If we choose the normal boot they will some time boot OK. The only way they do not experience this problem is by doing a total shut down and power off. Let them sit for a couple of minutes and then they will re boot properly with out any problems. Any one with a suggestion is greately appreciated.