Model Server Failed to launch

I use Design Management 6.0.5 on a Linux system. When I want to preview a diagram in Design Manager the preview displays the message "Unable to load diagram".

The Design Manager's Diagnostics (Application Administration -> Diagnostics -> Rhapsody Rendering Diagrams Application) shows this error message: "Model Server Failed to launch."

There are some new processes with the name mwgetmode, mwtrue and regedit. They consume 100% of my CPU. Here is the process tree (created with pstree):

inner-watchdog
    mwrpcss
    regss
        mwfwrapper
            mwadm
                mwperl
                    mwperl.bin
                        mwcore
                            mwperl
                                mwperl.bin
                                    core_services.c
                                        mwpingreg
                                            mwtrue
                                                6 x mwtrue
        6 x gegss
java
    ModelServer.exe
        ModelServer.exe
            mwadm
                mwperl
                    mwperl.bin
                        wstatus
                            mwstat
                                mwgetmode
                                    6 x mwgetmode
            set
    409 x java
 
I have installed already the 32bit system library libXdmcp.

Here are the entries in dm.log:

2018-03-09 14:48:53,349 [   Default Executor-thread-149] [] ERROR com.ibm.rational.carter.modelserver.ModelServer  - Failed model server:30001
2018-03-09 14:48:53,349 [   Default Executor-thread-149] []  INFO com.ibm.rational.carter.util.DiagramCacheManager  - Failed to render diagram https://myserver0491.com:9443/dm/models/_PuvGMSMTEeitlvBcXosP_A~GUIDbf6ae89b-a541-40b7-a616-401f4b39f2c3
2018-03-09 14:48:53,355 [   Default Executor-thread-149] [] ERROR com.ibm.xtools.rmpx.common.exceptions.RmpxRuntimeException  - <rdf:RDF
    xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
    xmlns:err="http://jazz.net/xmlns/prod/jazz/foundation/1.0/">
  <rdf:Description>
    <err:detailedMessage rdf:datatype="http://www.w3.org/2001/XMLSchema#string"
    >
User: user01
Rmps Request Line:
  GET https://myserver0491.com:9443/dm/diagrams/image?diagramUri=https%3A%2F%2Fmyserver0491.com%3A9443%2Fdm%2Fmodels%2F_PuvGMSMTEeitlvBcXosP_A~GUIDbf6ae89b-a541-40b7-a616-401f4b39f2c3&amp;rmps.context=https%3A%2F%2Fmyserver0491.com%3A9443%2Fdm%2Fcm%2Fstream%2F_P0TitiMTEeitlvBcXosP_A&amp;1520603243161&amp;ts=1520603243161 HTTP/1.1
Rmps Request Headers:
  Host: myserver0491.com:9443
  User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:58.0) Gecko/20100101 Firefox/58.0
  Accept: /
  Accept-Language: de,en;q=0.5
  Accept-Encoding: gzip, deflate, br
  Referer: https://myserver0491.com:9443/dm/web/projects/Demo01%20%28Design%20Management%29?oslc_config.context=https%3A%2F%2Fmyserver0491.com%3A9443%2Fdm%2Fcm%2Fstream%2F_P0TitiMTEeitlvBcXosP_A
  Cookie: JAZZ_AUTH_TOKEN=da955a581ea748aasfafe54846c41bba6d63d5WfwUV13GlABaDA; jfs-oauth-access-token0=da955a581ea7d58496cd41bba6d63d; jfs-oauth-access_token-secret0=OvpNDu55aOvLLnQMaCnOl7a5SbO5WfwUV13GlABaDA; JSESSIONID=00006OSM3tlqRfIiCi7Rz3XAGCu:e0c7d678-1d08-4ad0-af60-ab9b7957a4f9; LtpaToken2=fZj5o9M5+HkBWgQ89Y5LkrFrT...
  DNT: 1
  Connection: keep-alive
  X-ibm-internal-dm-request-correlation-ID: 7ad85231-afcc-4800-b5b0-ef51c46e4bd5

Details :
com.ibm.xtools.rmps.frontservice.jaf.common.jfsclient.RmpsRuntimeException: 400 (null) :ERROR: Model Server is not running
</err:detailedMessage>
    <err:errorMessage rdf:datatype="http://www.w3.org/2001/XMLSchema#string"
    >ERROR: Model Server is not running</err:errorMessage>
    <err:errorStatus rdf:datatype="http://www.w3.org/2001/XMLSchema#long"
    >400</err:errorStatus>
  </rdf:Description>
</rdf:RDF>
<style type="text/css"> p { margin-bottom: 0.25cm; line-height: 120%; } </style>