Finder remains empty after installing Yosemite

I upgraded my MBP (2013) to Yosemite and now every second Finder window I open remains empty. I can switch between Applications, Documents or Desktop but I still can't see any symbol. If I close it and start a new window and I'm lucky everything works. But sometimes

I get a window where I can see the symbols (with boldly written names) but cannot scroll or move symbols.

After upgrading I reinstalled Yosemite and then afterwards made a new clean installation but I still got the same Problem..

Here is what the Console app says:

20.10.14 20:21:18,356 CoreServicesUIAgent[236]: unexpected message <OS_xpc_error: <error: 0x7fff7b798c60> { count = 1, contents =

"XPCErrorDescription" => <string: 0x7fff7b798f70> { length = 18, contents = "Connection invalid" }

}>

20.10.14 20:21:18,362 com.apple.xpc.launchd[1]: (com.apple.WebKit.Networking.A8BA6CC3-F8AE-483F-9EFB-8C8AF6F31FF2[417]) Service exited with abnormal code: 1

20.10.14 20:21:18,372 com.apple.xpc.launchd[1]: (com.apple.Safari.8836[414]) Service exited due to signal: Terminated: 15

20.10.14 20:21:18,376 com.apple.xpc.launchd[1]: (com.apple.WebKit.WebContent.664D4CFC-71A7-4F58-B008-20E8E1406181[468]) Service exited with abnormal code: 1

20.10.14 20:21:22,935 com.apple.xpc.launchd[1]: (com.apple.Finder[462]) Service exited due to signal: Terminated: 15

20.10.14 20:21:23,046 Finder[539]: assertion failed: 14A389: libxpc.dylib + 97940 [9437C02E-A07B-38C8-91CB-299FAA63083D]: 0x89

20.10.14 20:21:23,091 Finder[539]: Could not find image named '22F5A264-E427-48AF-B09A-8BE98A07DEDC'.

20.10.14 20:21:23,093 Finder[539]: Could not find image named 'CF6A30BD-971C-47C3-B669-F98248107C95'.

20.10.14 20:21:23,094 Finder[539]: Could not find image named 'B926BAA7-3367-4BF2-8E7A-5166CD0D7AB0'.

20.10.14 20:21:23,851 sandboxd[305]: ([302]) storeuid(302) deny mach-lookup com.apple.dock.server

20.10.14 20:21:23,895 com.apple.xpc.launchd[1]: (com.apple.quicklook[543]) Endpoint has been activated through legacy launch(3) APIs. Please switch to XPC or bootstrap_check_in(): com.apple.quicklook

20.10.14 20:21:25,038 Finder[539]: Attempt to use XPC with a MachService that has HideUntilCheckIn set. This will result in unpredictable behavior: com.apple.backupd.status.xpc

Hope anybody can help me out.

Thanks

bluephoenox