hdd space disappearing

Hello.

I couple of days ago i was forced to use pc renew after a some problems with my new gpu.

Yesterdy it began to act strange. my x51 r2 did something strange. When it came to the alienware loading screen, it restarted.

After that it booted normaly. Also, parts of my hdd space seem to shrink. I split my 1 TB hdd into two partions. C: the windows drive and E: (this is the partition that is shrinking. as in the available space becomes smaller.) today I lost almost 20 GB. It does it upon start up apparently. I don't think it's a virus, so I'm currently trying to figure out what the problem is. I'm suspecting something with recovery or something like that.

PLease help.