In some cases rFactor looks like it is not doing anything while waiting for track or car to load.

In this case, alt-tab to desktop, click on rFactor icon in taskbar and you likely get error dialog (pop-up).

Take note of the error message, this is used to determine next chapter..

SHWFLOOR.GMT is used as "showroom" in the rFactor main UI.
Some mods change this or configuration so that it does not work properly.

To get back to working do the following:
1. open folder rFactor\GameData\Vehicles
2. locate file Vview.scn there and open it in notepad
3. near beginning there is line like this:
MASFile=Showroom.MAS
4. change it to something like this:
MASFile=GAMEDATA\VEHICLES\Showroom.MAS
5. save file and start rFactor

Usually there are two kinds of problems with mods:
either some file is missing or some file should not be there.

1. If a file is missing best chance is to redownload the mod from somewhere and hope it is ok.

2. Same error you get if there is something extra in the mod folder.
For example, readme.txt might slip in there easily and rFactor will try to process that for mod information.
In this case just delete files like .txt and .pdf from mod folder and try again.

3. Sometimes a mod is just broken and needs to be fixed. There's various tools for track editing and so on.

Trying to figure out the problem here, might be something that has been fixed already..

Likely a mismatch of mod files: using some files from older version of the mod perhaps.
Reinstalling mod should fix.

If it still does not work, check for the place where track is installed (the PLR file in userdata should have full path).

Check for SCN file in track folder (or sub-folders):

• look for MAS filenames and compare to those included with the track, fix names if necessary
  
• check SearchPath and copy MAS files to suitable locations

Also check you don't have multiple tracks with same name.

In case main menu does not load when starting rFactor you can reset selected mod by this:

• open folder: rFactor\UserData\<username>
  
• open file <username>.PLR in notepad
  
• in the PLR file, set value of Game Description to "" or change to another rfm
  
• save PLR and start rFactor, select another mod

This problem might be caused by some error in rFm files: try reinstalling a mod if this repeats.
Problems in rFm files that can cause this:

• bad UIData path
  
• bad OptionsDir path
  
• problem in OSC files
  
• etc.

I'll add information as I find out more..

In one case I found out that following steps help starting:
* delete mod-related directory under UIData (for example, UIData\EnduranceSeries)
* delete mod-related shaders under GameData\Shared (for example, GameData\Shared\EnduranceSeries)

I don't know yet why this helped, possibly some mismatch with some other data.

Also check rfm file(s) for "obvious" problems like changing UI or similar, remove or comment out any of following under ConfigOverrides:

• OSCFile
  
• OptionsDir
  
• ShadersDir

In case rFactor loading returns desktop early (before main UI) problem is sometimes in rFm file with wrong information or missing data files (vehicle data).

Problem is that rFactor may scan each rFm file and if there are old/broken mod information that will end whole loading of rFactor.

So always cleanup rfm folders when having trouble.