If it helps narrow it down: does WACUP produce a crash dump or an entry in Windows Event Viewer (Application log) when you hit Configure? A lot of old Winamp-era vis plugins call into the config dialog with an HWND/API assumption that doesn't quite match how WACUP hosts them (vs original Winamp), so the crash is often specifically in the config path rather than the visualization itself running fine otherwise. If you can grab the exception address/module from the crash (or just enable "keep debug info" if WACUP has that toggle under preferences) and post it here, that's usually enough for someone who knows the plugin API to tell whether it's a WACUP hosting issue or something in the plugin's own config code that never got updated for newer OS versions.