What if Vista can't go to sleep?

Q: Why can't my laptop go to sleep? I can only enter it when I just installed Vista. I don't know what happened. I clicked after I quit and I just can't go to sleep. .
A: Vista still uses the Windows XP sleep mechanism. If the system partition (usually the C drive) does not have enough space to save the hibernation file (comparable to the physical memory size), the computer will not go to sleep. Therefore, check if the remaining space on your system disk is sufficient. If not enough, delete junk files and useless files, and clean up unnecessary components and uninstall unused software to make room.