Kerbal Space Program

Hmm, I have extensively walked around the Space Centre with Kerbals and can't say that I've fallen through ever. What Graphics settings are you running KSP on?
You can simply attach your settings.cfg if you wish.

I've attached the settings.cfg and a few screenshots. I thought perhaps it was because my Terrain detail was set to low so I tested it with the highest setting and ran into the same problems. On further testing it appears to happen between the texture seams you can see in the zoomed out shot.

No mods; fresh Steam install.
Windows XP
Radeon HD 3650

I've tried SM3 shaders on/off (card support 4.1)
Tried with force part shader / no SM3
Changed other options around even anti-aliasing, shadows, and lights
Terrain set to medium setting minimized the effect but it is still present.

I also noticed floating buildings and polygons in the outside areas that I think is related. The polys on my ship and in the ship building area are fine. I attached another image to show what I mean.

Im also having the issue where my kerbals are sinking into the terrain. So far I have determined that it happens to me on Kerbin and on Eve. It didnt happen on the moon. I couldnt tell if it happened on Minmus. Driving Rovers in these conditions (at least on Kerbin) will result in wheels falling off or breaking every few dozen meters. At least on one occasion a kerbal "poofed" into oblivion after touching Kerbin. Im using 0.20

Sorry if this isnt a related bug but it appears related (maybe .)

I'm getting this on 21.1 unmodded

Kerbals will sink into the ground as they walk. They occasionally pop back to ground level, then sink again as they continue to walk. Sometimes they fall through the ground completely, before reappearing at ground level. Jumping usually resets them to ground level. Occasionally jumping, or touching another object, whilst sunk causes them to poof to death (naturally, this only happens on genuine missions and not when I'm trying to demonstrate the bug). Grabbing a ladder whilst sunk sometimes causes them to be launched several meters into the air.

nothing suspicious appears in the debug log, however when I got the "jump and die" version of this bug the log showed;
[WRN 03:41:27.636] Vessel Bill Kerman crashed through terrain on Kerbin
[LOG 03:41:27.639] [00:00:28]: Bill Kerman crashed into Kerbin.

I'm not 100% sure, but it seems to happen most frequently on hilly ground.

Attached is a save which demonstrates the problem. When I load this, the Kerbal starts buried up to his stomach, as pictured. Walking around causes him to drop in and out of the ground every meter or so. Climbing the ladder is quite tricky; sometimes he refuses to grab it (presumably when it's too high up), other times he'll launch himself into the sky.

I have terrain on low detail, SM3 on.

Closing this report out for now. If you find it is still occuring in the latest version of KSP please open a new report (and this one can be linked to it.) For best results, the wiki contains really useful info for when creating a report http://bugs.kerbalspaceprogram.com/projects/ksp/wiki.

You can also ask questions about the bug cleanup in the forum here: http://forum.kerbalspaceprogram.com/index.php?/topic/143980-time-to-clean-up-the-bug-tracker/ and tag @TriggerAu to get my attention