4.3.20 broken with Server 2003 /XP64
VirtualBox-4.3.19-96800-Win.exe still worked. VirtualBox-4.3.19-96823-Win.exe was the first build I tested afterwards and which was broken.
00:00:06.082111 VMSetError: F:\tinderbox\win-4.3\src\VBox\VMM\VMMR3\PDMLdr.cpp(307) int __cdecl pdmR3LoadR3U(struct UVM *,const char *,const char *); rc=VERR_SYMBOL_NOT_FOUND
00:00:06.082361 VMSetError: Unable to load R3 module D:\Program Files\Oracle\VirtualBox/VBoxDD.DLL (VBoxDD): GetLastError=127
00:00:06.260338 ERROR [COM]: aRC=E_FAIL (0x80004005) aIID={8ab7c520-2442-4b66-8d74-4ff1e195d2b6} aComponent={Console} aText={Unable to load R3 module D:\Program Files\Oracle\VirtualBox/VBoxDD.DLL (VBoxDD): GetLastError=127 (VERR_SYMBOL_NOT_FOUND)}, preserve=false
00:00:06.331826 Power up failed (vrc=VERR_SYMBOL_NOT_FOUND, rc=E_FAIL (0X80004005))
00:00:06.367666 UIMachineView::storeGuestSizeHint: Storing guest size-hint for screen 0 as 640x480
00:00:06.379257 OpenGL Error: Render SPU: (MakeCurrent) failed to make 0x35010bb5, 0x10000 current with 0x6 error.
00:00:06.379266 AssertLogRel F:\tinderbox\win-4.3\src\VBox\GuestHost\OpenGL\util\error.c(60) void __cdecl crError(const char *,...): <NULL>
Thank you for the report. We will most likely fix the Windows 4.3.20 package.