So, jetzt habe ich endlich das Problem gelöst indem ich folgende Sachen ausprobiert habe:
Zuerst über Eigabeaufforderung folgendes eingegeben: sfc /scannow (Stellt wohl Systemdateien wieder her), aber keine Treiber gefunden
Dann von Vista DVD gebootet und folgendes gemacht:
Step 1
Insert your Vista setup DVD and boot your PC from that by pressing any key when prompted;
Step 2
When it ask you for your language, be sure only to choose the one matching your current keyboard layout and click “Next”;
Windows is ready to install… but you MUST click “REPAIR YOUR COMPUTER” option, in the lower left corner of the window;
Step 3
System Recovery will look for installed operating systems: once found, click it and then click “Next”;
Step 4
A quick scan for common problems will start: if something wrong is found you’ll be prompted for an automatic system restore, that you should abort by clicking “Cancel” button.
Step 5
Now you should see the “System Recovery Options” window: select “Command Prompt” and prepare yourself for a DOS session…
Step 6
Go in your system disk by typing C: (or the letter corresponding to your system disk, followed by a colon):
Step 7
reach your INF system folder by typing: CD \Windows\INF
Step 8
Set a variable to let the file listing being sorted by extension (file type) and then by name, with folders grouped at the top by typing the following command: SET DIRCMD=/p /a /ogen
Step 9
Let’s get the files list by typing: DIR
You’ll see an enormous amount of INF and PNF files, a bunch of subfolders and a few files having different extension and a really recent date.
Step 10
Type each one of these commands with care and being sure that your command prompt is pointing to \Windows\INF folder:
DEL DRVINDEX.DAT
DEL INFPUB.DAT
DEL INFSTOR.DAT
DEL INFSTRNG.DAT
DEL INFCACHE.*
DEL SETUPAPI.*
All of the above files shouldn’t be write-protected nor hidden, so you don’t have to see any error following each command.
Step 11
When finished, type EXIT and the command prompt window will close itself.
Click “RESTART” button and remove Vista Setup DVD from optical unit.
Now that you have completely destroyed the built-in database, Windows will launch its rebuild at the first time you’ll plug a new Plug’n'Play peripheral or when you’ll start the “Add new hardware” procedure in Control Panel.
Und siehe da, nach neuem Treiber unter: C:\WINDOWS\SYSTEM32\DRIVERSTORE\ gesucht und plötzlich gingen alle meine USB Mass Storage Devices wieder.
Aber vielen Dank für die Hilfe hier im Forum.