Hello XWiki users,

being an absolute newbie with XWiki one of the first things after getting somewhat familiar with the concept, I tried to change the skin.

I am running on an out-of-the-box installation on MS Windows with HSQLDB and Jetty.
I changed it using the Administration link to, for example "finch" skin, but many of the scripts seem to have stopped working afterwards and I get a number of errors like the following when I try to change the skin back to "albatross".

14:58:55,018 ERROR P1-19 http://localhost:8080/xwiki/bin/view/Panels/PanelWizard
?forceLeftPanels=1&forceRightPanels=1 SimpleLog4JLogSystem:logVelocityMessage:15
4 - Left side ($!hidecolumns) of '==' operation has null value. If a reference,
it may not be in the context. Operation not possible.  [line 6, column 21]
15:14:17,580 ERROR P1-19 http://localhost:8080/xwiki/bin/view/Main/ SimpleLog4JL
ogSystem:logVelocityMessage:154 - VM #breadcrumb: error : too few arguments to m
acro. Wanted 3 got 2
15:14:17,580 ERROR P1-19 http://localhost:8080/xwiki/bin/view/Main/ SimpleLog4JL
ogSystem:logVelocityMessage:154 - VM error breadcrumb. Null AST
15:14:17,580 ERROR P1-19 http://localhost:8080/xwiki/bin/view/Main/ SimpleLog4JL
ogSystem:logVelocityMessage:154 - Left side ($!hidecolumns) of '==' operation ha
s null value. If a reference, it may not be in the context. Operation not possib
le.  [line 6, column 21]
15:15:16,959 ERROR P1-18 http://localhost:8080/xwiki/bin/admin/XWiki/XWikiPrefer
ences SimpleLog4JLogSystem:logVelocityMessage:154 - Left side ($global) of '!='
operation has null value. Operation not possible.  [line 30, column 83]
15:15:16,989 ERROR P1-18 http://localhost:8080/xwiki/bin/admin/XWiki/XWikiPrefer
ences SimpleLog4JLogSystem:logVelocityMessage:154 - VM #breadcrumb: error : too
few arguments to macro. Wanted 3 got 2
15:15:16,999 ERROR P1-18 http://localhost:8080/xwiki/bin/admin/XWiki/XWikiPrefer
ences SimpleLog4JLogSystem:logVelocityMessage:154 - VM error breadcrumb. Null AST

What did I do wrong?

Thanks for any help.

Wolfgang