Here is my description in the Service log sent to Bentley (ticketno:[7000025886]), maybe someone else had the same problem and they do have a simple workaround:
I have installed MX SELECTseries3 from mx081109494en_au.exe and the product fails to load correctly
after installation. I have submitted error reports when this has occurred.
When starting using either MX ROAD or MX ROAD Microstation the product starts
ok and the tips box appears. I OK this and the MX Project Startup dialogue box
appears. I create a new project fill in the appropriate name and file location
and deselect the string naming convention. I click ok and click yes in the next
box to set standard file locations. Then MX just stops and the report error to
bentley box appears. After submitting the error, MX appears to open.
On exiting a popup box appears showing Microsoft .NET Framework as the heading.
The contents read 'Unhandled exception has occurred in a component in your
application. If you click Continue, the application will ignore this error and
attempt to continue. External component has thrown and exception '.
The error coding is attached. When press continue as this is the only option
available to proceed, MX crashes again showing the report to Bentley boxes. I
report to Bentley and then a Problem notification box appears indicating a log
has been stored.