All objects which are using texture with alpha channel (trees, fences) have problem with shadows. In some situations shadows are missing or we can see flickering.
Post exact graphics settings and driver version. I don't have problems like these except for Croft where tree shadows dissapear completely in external cameras, while working fine in cockpit view. GeForce 450 GTS / Driver version 296.10 All ingame settings to maximum, except for shadow blur (different settings work fine aswell). Config settings: HDX, FXAA, no sync, AA x2
HDR - ON, FXAA - ON, no sync, all settings to max, driver Catalyst 12.4, Win7 64 It happens on all tracks.
I noticed the same issue with Monaco just now. Only the shadows from the trunk are rendered, nothing from the leafs. Worse still, for me at least it only appears from the external cameras like the trackside tv cams. The main cams (cockpit, nose, tv cockpit, ...) are fine.
This heavy flickering happens for me too. Tested on Mills with all settings on max, HDR on, FXAA on, no sync. Tree shadows disappear completely.