
If Demoplayer gets stuck on 'writing cfg.', this means UAC is blocking it from writing a file under C:\Program Files.


All you need to do:
Right Click Demoplayer.exe > Properties > Compatibility Tab > check 'Run As Admin' as shown in UAC.png
Another Option is to lower your UAC settings


To play Demos:
Right click a demo file (.dm_1) and 'open with..' then check 'always open with' and look for Demoplayer.exe,
to associate the demo files with it.
as shown in AssociateDemos.png