I'm running Windows 7 x64 on a 50Gb disk partition. A few days ago I noticed that I had only 2.5 Gb space left, which i considered unusual, but after a restart it came back to +4Gb space so I didn't make much of it.

This morning I noticed that I had 12Gb free space, but since I was a bit worried about the constant changes in free disk space I kept an eye on it and it started to decrease slowly.

After 2 hours I had only about 4.7 Gb left, so I started to try to free up space. Disk clean up saved me only 250 Mb, recycle bin was empty. Browsing history and download history also didn't save me any remarkable amount.

Removing all restore points same, I have only 1 day saved anyway. But every restart the disk space decreased little bit.

I ran a virus scan and malwarebytes scan which found nothing. I did a disk fragmentation which resulted in a 1Gb decreased space. I didn't know that defragmenting used disk space.

So now I'm down to 2.5 Gb free space and I haven't done any downloads or watched videos all day.

Any ideas which can help me ?

Solved already, a Google result directed me to a forum which advised me to download Treesize.

That software locates all the big files on your disk, and found that I had 10 Gb in " roaming " in a temporary file from some software .

Deleted the file and done.

I can understand your being perplexed, I would be. 10 Gb "roaming" ??!!

When you do a Clean Up of your C drive in Windows, always go to More Options and clean up System Files, and delete all Restore Points except the last one. I saved 15GB on a 60 GB SSD !

I can understand your being perplexed, I would be. 10 Gb "roaming" ??!!

The directory is poorly named. It is found in Appdata\user name\roaming. It is where Windows puts data it may need when programs are opened. Often it stays there after the programs are closed. It is useful in an enterprise server environment where your data is in your account in active directory and you "roam" from computer to computer within the enterprise.

CCleaner will get it.