SVN/Tortoise error "assertion failed"

Hi all,
Recently, I switched to TortoiseSVN-1.7, made an upgrade of the SVN
working copy, and tried to run the first SVN update. I got the following
error message.
Is there any help around?
Kind regards,
Silvia

Updating: C:\Users\stackelb\Desktop\Documents\Muhannad-SVN\PSE-SS-2013
Error: In file
Error:
'D:\Development\SVN\Releases\TortoiseSVN-1.7.12\ext\subversion\subversion\libsvn_wc\update_editor.c'

Error: line 1315: assertion failed (added_status ==
svn_wc__db_status_added ||
Error: added_status == svn_wc__db_status_copied || added_status ==
Error: svn_wc__db_status_moved_here)

-- 
Dr.-Ing. Silvia von Stackelberg
Am Fasanengarten 5, 76131 Karlsruhe / Gebäude 50.34 Raum 365
Tel. +49 721 608-47351
Karlsruher Institut für Technologie (KIT)
Fakultät für Informatik
Institut für Programmstrukturen und Datenorganisation (IPD)
Lehrstuhl für Systeme der Informationsverwaltung
KIT - Universität des Landes Baden-Württemberg und nationales
Großforschungszentrum in der Helmholtz-Gemeinschaft