Hi François,
this is what it looks like:
Date    Level    Logger    Message
08:36:27    INFO    org.openlca    set log-level=INFO
08:36:27    INFO    org.openlca.app.rcp.RcpActivator    start openLCA 2.0.0, install location=C:\Program Files (x86)\openLCA, workspace=C:\Users\abecker\openLCA-data-1.4
08:36:27    INFO    org.openlca.nativelib.NativeLib    load native libraries from C:\Program Files (x86)\openLCA\olca-native\0.0.1\x64
08:36:27    INFO    org.openlca.app.App    loaded native libraries; with UMFPACK=false
08:36:34    INFO    org.openlca.core.database.Derby    initialize database folder C:\Users\abecker\openLCA-data-1.4\databases\ecoinvent_391_cutoff_upr_n2_amrei_18_05_1, create=false
08:37:31    INFO    org.openlca.core.math.SystemCalculator    calculate result for RootEntity [type=Process, refId=1d57c973-328e-4153-abe1-53ca7cb23e6a, name=Glycolysis - case 1 (PET100) DE]
08:38:22    INFO    org.openlca.core.math.SystemCalculator    selected provider org.openlca.core.results.providers.FactorizationSolver@4ad853ef
08:38:55    ERROR    org.openlca.app.results.InfoPage    Matrix error: the matrix is probably singular.
Processes, which I haven´t touched and which worked 2 days ago all get the same error message.