More than 100 GB disappeared on MacBook Pro 250GB SSD

I was installing a software on the MacBook Pro of my girlfriend when I have found that in " > About this Mac > Storage", it says that she have 134 GB of space used by "Applications"...

I have then looked at what she installed, and I see that the only apps she installed are Caffeine, Kindle, VLC, Google Chrome and Skype (along with the default applications of OS X).

I've downloaded Disk Inventory X to see what's happening, and it says that the Applications are taking up about 9GB.

The question then is... Where are all these gigabytes gone?

PS: Using the "Disk Utility" app, it says that 130 GB are used by Applications, but it also says that there are 202 GB of free space... I wonder how this can be possible since the SSD is just 250 GB...

Maybe, the Spotlight is not indexing correctly any more.

Open the System Preferences > Spotlight/Privacy and drag the Macintosh HD icon to the window. Click OK. Choose the icon and and click the - sign to remove it, so that the reindexing routine starts. Test when completed.