sounds like your operating system has been corrupted. Usually via a recent windows update. If the startup repair doesn't sort it or you cannot get windows to start via safe mode then 9/10 it needs a system re-install repair.
It can be done on Vista [just about] but not as easy as it was in XP. Theres a good article here about Repair Vista using the XP re-install repair method
Try safe mode first - sometimes you can get lucky and it will boot into windows. usually then you can do a full shut down as normal and it then reboots. The problem your getting usually occurs because windows didn't shut down properly when you last shut it down and it's generally caused by an update.
To get into safe mode - as soon as you power up the laptop - tap the F8 key until you get a list appear. In vista the first option is startup repair or safe mode. Your other option without having to do a repair install is to try a boot repair .
In the startup repair advanced options - open the command prompt console and type the following
Either one or all three of those - generally the first or second option will fix the boot issue - if it doesn't then it's the repair install option you'll need.