I'm having weird issues with my internal Fusion Drive. 

**Symptoms**:

 1. it gave itself a new cryptical name, and I can't change it back
 2. in most cases I cannot install new software anymore (e.g. I cannot update Flash)
 3. It is sometimes shutting down immediately
 4. Disk Utility says "no errors found" but can't mount it.


**See below for some screenshots:**

*Referring to Point 4 and 1* (says: Volume seems to be ok, see the weird name...)

[![enter image description here][1]][1]


*Referring to Point 2* (says: Installation failed)

[![enter image description here][2]][2]

Error while mounting Flash Player installer image:

    26.11.15 10:03:42,000 kernel[0]: hfs: mounted Adobe Flash Player Installer on device disk3s1
    26.11.15 10:03:42,082 mds[55]: (Volume.Normal:2464) volume:0x7fb9ef004600 ********** Bootstrapped Creating a default store:1 SpotLoc:(null) SpotVerLoc:(null) occlude:0 /Volumes/Adobe Flash Player Installer
    26.11.15 10:03:53,137 authexec[510]: executing /Volumes/Adobe Flash Player Installer/Install Adobe Flash Player.app/Contents/MacOS/Install Adobe Flash Player
    26.11.15 10:04:14,000 kernel[0]: hfs: could not initialize summary table for Flash Player
    26.11.15 10:04:14,000 kernel[0]: hfs: mounted Flash Player on device disk4s2
    26.11.15 10:04:17,000 kernel[0]: hfs: unmount initiated on Flash Player on device disk4s2

diskutil cs output from Terminal:

    CoreStorage logical volume groups (1 found)
    |
    +-- Logical Volume Group BD4DE488-7C63-4FBA-9FAC-9B92CD56EDE4
    =========================================================
    Name:         FusionDrive
    Status:       Online
    Size:         1249060388864 B (1.2 TB)
    Free Space:   0 B (0 B)
    |
    +-< Physical Volume C106FB79-47F5-4967-924F-043C553FC58E
    |   ----------------------------------------------------
    |   Index:    0
    |   Disk:     disk0s2
    |   Status:   Online
    |   Size:     249715376128 B (249.7 GB)
    |
    +-< Physical Volume 6492048E-B397-4457-A12B-DA62DD379B35
    |   ----------------------------------------------------
    |   Index:    1
    |   Disk:     disk1s2
    |   Status:   Online
    |   Size:     999345012736 B (999.3 GB)
    |
    +-> Logical Volume Family 40A9F389-D3F0-4D75-89A3-36FFAEA6FD57
        ----------------------------------------------------------
        Encryption Status:       Unlocked
        Encryption Type:         None
        Conversion Status:       NoConversion
        Conversion Direction:    -none-
        Has Encrypted Extents:   No
        Fully Secure:            No
        Passphrase Required:     No
        |
        +-> Logical Volume E02059A8-E5D4-4DFF-9D0F-49408380838E
            ---------------------------------------------------
            Disk:                  disk2
            Status:                Online
            Size (Total):          1242500358144 B (1.2 TB)
            Conversion Progress:   -none-
            Revertible:            No
            LV Name:               ´+ßPÜÜÜÜÜPÜ09O8UI9OOOOOOOIOO09O987UUUUZU6T786Z65444RRRR3ERR5EREREREER5R4E43E4ED43ERE3434R43RE3ER4E3R45REW4W45W343E43W424323231QWQ3W3W23432123432323E23E21W23453213E43212R2WEW1221QQ^21
            Content Hint:          Apple_HFS


**my counteractions so far**

1. ran the Apple Hardware Test. Result: nothing found.
2. ran the First Aid (see screenshot). Result: nothing found.

Any help is much appreciated! Wanna get rid of this :(

  [1]: https://i.sstatic.net/FVzse.png
  [2]: https://i.sstatic.net/PnQj1.png