You do not need OMDev folder. Remove that and also remove OMDEV environment variable if you have it.

You could also try the nightly-builds:
https://build.openmodelica.org/omc/buil … ly-builds/
as we fixed a lot of issues in the compiler since 1.9.3.

Thanks for the recommendation. I tried to install the latest nightly build OpenModelica-v1.9.4-dev-578-ga08261b.exe but it made my Windows explorer freeze and I wasn't able to install it However, I tried to install the OpenModelica-v1.9.3 release again, this time as administrator, and I was able to compile a Modelica model. I got the message "compilation process finished sucessfully" but then OMEdit started to freeze (OMEdit window not responding). Do you have any idea what could cause this problem?

Check your activity monitor and see if the simulation process is perhaps still running (you can kill it if you want to lose the simulation results).

Also check your firewall since the simulation process and OMEdit communicate via TCP/IP.

Thanks a lot! I can now compile the model. However I then run into this new problem:

c:/openmodelica1.9.3/mingw/bin/../lib/gcc/mingw32/4.4.0/../../../../mingw32/bin/ld.exe: cannot open output file Modelica.Mechanics.Translational.Examples.Accelerate.exe: Permission denied
collect2: ld returned 1 exit status
mingw32-make: *** [omc_main_target] Error 1
Compilation process failed. Exited with code 2.

How should I tell openModelica where to find ld.exe? Do I have to look at the compile.bat file? If yes, which lines do I have to change?

That messages says that "ld" cannot open Modelica.Mechanics.Translational.Examples.Accelerate.exe for writing (the C code was generated and now the  linker ld wants to build the executable) which means something is blocking it.
What kind of antivirus do you have?

I have Avast Free Antivirus. I  turned it off and I still get the same error I launched OpenModelica as adminstrator. What could it be?

I realized that I can simulate certain example Modelica models such as Modelica.Mechanics.Translational.Examples.Oscillator. However, I get this same error when simulating Modelica.Mechanics.Translational.Examples.Accelerate

c:/openmodelica1.9.3/mingw/bin/../lib/gcc/mingw32/4.4.0/../../../../mingw32/bin/ld.exe: cannot open output file Modelica.Mechanics.Translational.Examples.Accelerate.exe: Permission denied
collect2: ld returned 1 exit status
mingw32-make: *** [omc_main_target] Error 1
Compilation process failed. Exited with code 2.

So the error is specific to this example model!?

It could be that a process got stuck while writing or executing that file. Have a look in task manager to see. I would suggest also a computer restart.

I know now is late, but for recording and future users:

I had the same problem as described above, and the cause of it was that I had my file saved in a folder named with a word with accents.

When I removed all accents and possible weird things from the name of the folder, everything came back to normal, the simulation ran beautifully and the compiler wasn´t stopped anymore, hahahaha.

Good luck!