OMD Nagios web sidebar duplicated

I encountered a strange issue with the nagios web interface . From time to time , something is duplicating the sidebar .I cant find errors inside the apache log to indicate the root couse
The first problem that i noticed came from script which was trowing an internal server error on the webpage for every logged error ( for example when a user failed to authenticate), which honestly we dont need to be shown as internal server error on the webpage .I tried to make an exception , so i changed as a test the value from error to crit . The internal server error does not appear anymore, but instead the sidebar is beeing duplicated .

if req.myfile == “crit”:
return apache.OK
except Exception, e:
req.write("<html><body><h1>Internal Error</h1>Cannot output error log: %s</body></html>" % e)
return apache.OK

Has anyone encountered a similar error ?