Galaxy S2 app storage problem

Hello, I am having issues with the app available storage and updating/installing new apps.

Device: Samsung Galaxy S2
Android version: 4.1.2

Storage:
-Total space: 1.97GB
-Applications: 0.96GB
-Available space: 249MB

Issues:
1. As you can see the available space should be 1GB, instead it says 249MB.
2. I can't upload/install new apps. I am getting an "location" error.

Actions taken at this moment:
1. Downloaded "app cache cleaner". It recovered about 50mb.
2. Deleted all the photos I had to see if it had any effect. This didn't help at all.
3. Restarted the phone to see if it was a temporal error.

So...
1. Why is the available space 800mb less that it should be?
2. How can I fix that?

Thanks in advance for your help. Have a nice day.

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