My 120GB SSD have Battlefield 3, Starcraft 2 and hearthstone on it.
i delited everything else(20GB) i didnt need when i first saw it was in the red area and now its back on red (1,2GB left) when i havent installed a single thing.
spybot / avg / avast / malwarebytes cant find any viruses.
Have a look for a program called space sniffer, it will tell you what's using your disk space. How much ram do you have? Because if you have the page file set to automatic it will use as much space as the ram you have, so if you have more than 8GB or memory then manually set your page file to 4 or 8gb to stop it wasting all that space.
Disable and delete the hibernation file on the disc then remove of lower the size of windows page file.
If you have 8gbs of ram installed windows will take up 8gbs of space on your hdd for pagefileing.
Follow this http://www.overclock.net/t/1156654/seans-windows-7-install-optimization-guide-for-ssds-hdds to optimise your ssd space and speed wise.
Yeah the hibernation file is what is probs is, I have a 120GB as my C drive and I was in the same exact position as you I had no idea then when I used one of those programs (i forget which now) I saw it was that hibernation thing.