Thanks for your reply.
I did what you described, but when I pressed play at the Social Club popup-window, it just said "Grand Theft Auto IV has stopped working" like before ;)
I have been reading other threads, and there are this checklist, which I have done as well:
Please do the following:
Make sure you aren't using a crack - We don't support cracks It isn't - I have bought the game on Steam
Update GTA IV to 1.0.7.0 (the latest version of the game, or 1.1.2.0 for EFLC) - This sometimes fixes a wide variety of issues My game is updated, at least it is saying that
Make sure that you run the game as an administrator. I do.
Make sure that your GTA IV root folder (and every subdirectory) is not set to "read-only" I have edited it so every folder (and subdirectory) is not set to "read-only"
Ensure that ScriptHook.dll, ScriptHookDotNet.asi and Dsound.dll OR Xlive.dll are in the GTA IV ROOT folder They are.
Ensure that there is a folder titled 'LCPDFR' in the ROOT GTA IV folder. There is.
Check that all the above files exist, if they do not, reinstall LCPDFR with the MANUAL installation. Currently I am using the manual installation -it din't work with the automatic.
Ensure that you are using up to date versions of every LCPDFR dependency and LCPDFR itself. I think I am.
Install these: .Net Framework 4.5, Microsoft Visual C++ Redist 2012 Done. It do still not work :(