Game just does not launch

Dear Support, sorry to bother, but I cannot launch LOTRO anymore.

I upgraded to windows 7 to windows 10. Then I could launch LOTRO, but with graphics really awful, low resolution, low fps.
Then, I installed amd-catalyst-15.7.1-win10-64bit , for my AMD RADEON HD 6700.
Graphics went better, but then impossible to launch LOTRO. I can login, select the world, and ... nothing happens, not even an error message.

I had similar problem with Win7: at the time I used a dirty workaround, installing again catalyst, and some setting went good, so I could play.
I could not find which setting to correct under win7, so I always used that dirty trick.
Now, it looks the issue is the same under win10, but I do not have any workaround.

I checked usual issues before posting, but did not found about my issue...
can you please help me solve this ?

regards,