A freebie Toolbar or other Malware can reset or erase the the Tabs in the Power options screen. Uninstall the freebie Toolbar. Or system restore to a day when all was well.
start, all programs, accessories, System Tools, System Restore
or
Download malware remover
http://www.techsupportteam.org/forum/tutorials/2282-malwarebytes-anti-malware-mbam.htmlhttp://www.microsoft.com/windowsxp/using/setup/learnmore/tips/magyar1.mspxTo enable hibernation support on your computer:
You must be logged on as an administrator or a member of the Administrators or Power Users group. If your computer is connected to a network, network policy settings may prevent this procedure.
1.
Click Start, click Control Panel, click Performance and Maintenance, and then click Power Options.
2.
Click the Hibernate tab, and then select the Enable hibernate support check box. If the Hibernate tab is not available, your hardware does not support this feature.
3.
Click OK to close the Power Options dialog box.
Note: When you put your computer into hibernation, everything in computer memory is saved on your hard disk. When you turn the computer back on, all programs and documents that were open when you turned the computer off are restored on the desktop.