How many SW have you installed on your machine?
If multiple versions are installed, make sure that the path through which SW is trying to access the dll file is right.
You can also manually load the respective dll files by below mentioned procedure
SW -> File -> Open -> Set File Type to 'Add-Ins(*.dll)'-> Go to C:\Program Files\SOLIDWORKS Corp\SOLIDWORKS\Simulation and you should find cosworks.dll -> Open it.
Same procedure for Toolbox.
I've noticed that when I install after performing a clean installation, erasing the record. the first time you run the program I get no error, but the next time if the error appears.
version was installed before 2015 SP 3 had the same problem and spent the 2016 version, thinking it was incompatibility issues with w10.
I tried what you say does but it does nothing
That seems strange behavior. I would suggest you to contact your VAR and get the issue resolved.
If necessary your VAR can contact SW technical support.