My miktex (32 Bit) 2.9 installation (on windows 7, 64 Bit) doesn't update (GUI and console).
I recognized the problem first on 2013-07-01. It seems to be caused by the package miktex-arctrl-bin-2.9 as the following lines from an elevated shell show.
C:\WINDOWS\system32>mpm --admin --update-db --verbose --install=miktex-arctrl-bin-2.9
downloading http://ftp.fernuni-hagen.de/ftp-dir/pub/mirrors/www.ctan.org/systems/win32/miktex/tm/packages/miktex-zzdb2-2.9.tar.lzma...
677286 bytes, 2449.67 KB/Sec
updating package definition directory ("C:\Program Files (x86)\MiKTeX 2.9\tpm\packages")...
installed 136 package definition files
visiting repository http://ftp.fernuni-hagen.de/ftp-dir/pub/mirrors/www.ctan.org/systems/win32/miktex/tm/packages/...
repository type: remote package repository
loading lightweight database...
downloading http://ftp.fernuni-hagen.de/ftp-dir/pub/mirrors/www.ctan.org/systems/win32/miktex/tm/packages/miktex-zzdb1-2.9.tar.lzma...
134749 bytes, 1356.61 KB/Sec
starting package maintenance...
installation directory: "C:\Program Files (x86)\MiKTeX 2.9"
package repository: http://ftp.fernuni-hagen.de/ftp-dir/pub/mirrors/www.ctan.org/systems/win32/miktex/tm/packages/
lightweight database digest: 348d5562d8a8cb8e92530ca19eba0eb1
going to download 21784 bytes
going to install 6 file(s) (1 package(s))
downloading http://ftp.fernuni-hagen.de/ftp-dir/pub/mirrors/www.ctan.org/systems/win32/miktex/tm/packages/miktex-arctrl-bin-2.9.tar.lzma...
21818 bytes, 213.07 KB/Sec
visiting repository http://ftp.fernuni-hagen.de/ftp-dir/pub/mirrors/www.ctan.org/systems/win32/miktex/tm/packages/...
repository type: remote package repository
loading lightweight database...
downloading http://ftp.fernuni-hagen.de/ftp-dir/pub/mirrors/www.ctan.org/systems/win32/miktex/tm/packages/miktex-zzdb1-2.9.tar.lzma...
134749 bytes, 1144.27 KB/Sec
lightweight database digest: 348d5562d8a8cb8e92530ca19eba0eb1
mpm: The operation could not be completed because the following file failed verification:
mpm:
mpm: C:\Users\EBELIN~1\AppData\Local\Temp\mikEC80.tmp
I already tried to remove the (earlier existing but outdated) package miktex-arctrl-bin-2.9 but update and install fails. Cleaning the Temp storage directory and checking for file permissions there (temp) and in the install folder doesn't help.
Is there a solution without new installation?
Changing the repository to ...uni-erlangen... did not help – it results in the following screenshot: 
Best Answer
Inspired by @UlrikeFischer, I tried around with changing the repository.
Via the GUI I got no chance - but running
mpmfrom the console five times always with other errors (like timeout and file verifications errors) it finally went fine. Thanks.