Don't Do system restore..
I think while windows was updating your battery died and windows shut down, so the update was not installed correctly and now your windows is unstable..

Do the following before doing system restore. Re-installing or restoring is usually the last option..

Assuming you have Vista...
Go to control panel.
Open Programs and features.
On the Left panel, Click on "View Installed Updates"
find the Update that you were trying to install (You can sort by 'installed on' and find the one from latest date)
Uninstall that update and re-boot your laptop.
If problem is solved... Yeah.. Thank me,... and make sure you always have your power connected while installing updates.