rFactor2 will not start!

Hello...

yesterday I bought a GT3 Power Pack.
Today I launched Steam and then rFactor 2... a window was opened and I followed the download about GT3 object from Workshop.
At the end there was the refresh of the content Packages in the rFactor 2 launcher.
But when I tried to launch the game clicking on the (single player) helmet icon unfortunately nothing happens... the helmet does not remain colored orange but gray and rFactor 2 does not start!
In multiplayer mode instead the two helmets turn orange, I can choose from the list of online races but when I click on Join Race button the game still will not start!

Last night for technical problems I had to change the PC name in system property and then, after fixing the problems, I re-entered the original name.
Could this be the problem preventing the start of the game?

In any case, when I start rFactor 2 the launcher start and recognize my account (Doctor Kruntz) and the license info (Type: rFactor2 - Online Access: Lifetime) and the Startup Log indicates All mods and components verified.
There seems to be no obvious mistakes, but then, if I try to launch the game (both in single player and multiplayer mode) this does not start!
I also checked the files integrity which was perfect.

I do not know what to do anymore!

Can you help me to solve the problem?

 

Delete CBash and Shaders. Remove all plugins.

 

And make sure your firewall or virusscanner isn't messing up.

 

The same problem appears in DX9 and DX11 too.

 

I make a test with windows firewall down but problem persist!

 

J'ai le même problème depuis la mise à jour 1109 en dx9 ou dx11.
Le jeu ne commence pas (même pas le laucher).
J'ai réinstallé tout propre entierement, Meme stream le probleme persiste. Je ne sais pas quoi faire non plus)
réinstalle Windows ?

 

Component "rF2 Showrooms 1.0f" failed to verify, removed from inventory
et le jeu ne se lance plus

 

GOOD NEWS:

After I did all the possible tests following various advice, the problem continued to persist, so I reported the situation to the initial state and closed everything.
Today I have started rFactor 2 and everything seems to be back in order... the game not have problem with both single player mode and online multiplayer.
The GT3 package is present in the available car kit

I really can not explain what might have happened... but anyway, better so!
Steam and PC mysteries...

However, I thank all those who have tried to give me an help