Hi Harshid84,
The primary reason why computer restarts on hibernate is due to the incompatible hardware driver.
Method 1: Make sure that you have compatible drivers for the hardware on your computer. This is one of the main reasons which causes improper hibernate and which results in computer restart.
Refer the following link for more information:
Update a driver for hardware that isn't working properly
Method 2: Check this setting for keyboard, mouse and network cards.
Click on Start-> Type in devmgmt.msc-> In the Device manager Window double click on “Mouse” -> In the Properties Window-> Click on “Power Management” tab-> Uncheck the option : “Allow this device to wake the computer”. Click OK.
A program or scheduled task might be waking your computer. By default, Power Option settings do not allow scheduled tasks to wake the computer from sleep or hibernate. However, some programs might awaken the computer if these settings have been changed.
To prevent programs from waking your computer
1. Open Power Options by clicking the Start button , clicking Control Panel, clicking System and Security, and then clicking Power Options.
2. On the Select a power plan page, click Change plan settings for the plan that you want to change.
3. On the Change settings for the plan page, click Change advanced power settings.
4. On the Advanced settings tab, expand Sleep, expand Allow wake timers, choose Disable for both when your computer is running on battery and when it's plugged in, and then click OK.
Also you may refer this below link for further information.
Sleep and hibernation: frequently asked questions**http://windows.microsoft.com/en-US/Windows7/Sleep-and-hibernation-frequently-asked-questions**
Regards,
Divya R – Microsoft Support.