FSX Trust DLL Policy

From PMDG Ops

(Thanks to Steve Patrick at Spat's Weblog for this)

A few users are reporting that Flight Simulator X will not ask them to trust the PMDG DLLs (and will subsequently crash when loading the PMDG 747-400X). This will happen even if they remove the PMDG entries from the [Trusted] section of fsx.cfg.

Turns out there's a registry setting that Windows uses for third party DLL trust policy selection.

Check if the HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\WinTrust\Trust Providers\Software Publishing registry key is set to 0x63c00. This value is Microsoft's WinTrust policy selection flags, as described here. The 0x40000 flag means "Allow only items in personal trust database" and apparently, this clashes with FSX's ability to allow manual authorization of unrecognized DLLs, telling it instead to never trust anything outside the user's personal trust.

Unsetting this flag (putting it back to its default 0x23c00 value) returns all operations to normal and Flight Simulator X will once again be able to ask the user to designate the PMDG DLL modules as 'Trusted' software.