[airon]

Here's a portable installation package with the FFMPEG DLLs installed and a clean slate in terms of the Reaper.ini .

If this setup works on your machine, carefully import things one at a time, and backup the portable installation between each change. Import your key commands, then your toolbars and so on. You can export them separetely in the Preferences/General page from your usual installation.

If it works, backup your Reaper application support folder, remove it, uninstall Reaper (not the portable installation), export the complete config from the portable installation, install Reaper, copy the FFMPEG DLL files in to the Reaper program directory from the portable installation, start the installed Reaper, import the config from the portable one.... and that sucker should hopefully work.

If this portable installation works. Then again, perhaps it's a more basic error and a backup of your Windows system, then a fresh install is in order. It's easier to blow two hours on a system and audio software reinstall, than to agonize for another day. But try the stuff above first.

The portable installation, tested to work on my system. It's completely vanilla except for the added FFMPEG DLLs and the sound device choice (Direct Sound primary system driver).

-edit- Ok, the file's offline now. Hope it works.