hi:

I have get the uboot image (Dataflashboot-SAM9261EK-revD/u-boot-at91sam9261ek-642D-2006-09-16.bin)from ftp://81.80.104.162/AT91_Third_Party_Design_Flow/
and burn it to data flash address 0x8000 ,and when power up the target board ,and it seem ok ,

U-Boot 1.1.4 (Sep 16 2006 - 10:14:00)

DRAM: 64 MB
NAND: No NAND device found!!!
0 MiB
DataFlash:AT45DB642
Nb pages: 8192
Page Size: 1056
Size= 8650752 bytes
Logical address: 0xC0000000
Area 0: C0000000 to C00083FF (RO) Bootstrap
Area 1: C0008400 to C003DDFF (RO) U-Boot
Area 3: C003FF00 to C0041FFF Environment
Area 4: C0042000 to C018BFFF OS
Area 5: C018C000 to C083FFFF FS
In: serial
Out: serial
Err: serial
dm9000 i/o: 0x30000000, id: 0x90000a46
MAC: 00:04:25:fe:ed:92
operating at 100M full duplex mode
U-Boot>

but when I enter the command "tftp 20008000 myroot.cramfs "
(NOTE: I use the net chip is DM9000AEP (PLCC48) PACKET) replace the chip
dm9000)
it desplay follow message
tftp 20008000 myroot.cramfs dm9000 i/o: 0x30000000, id: 0x90000a46
MAC: 00:04:25:fe:ed:92
operating at 100M full duplex mode
TFTP from server 192.168.1.102; our IP address is 192.168.1.110
Filename 'myroot.cramfs'.
Load address: 0x20008000
Loading: T T T T #T T T T T T T T T T #T T T T T T T T T T T T T T T T T T T T T T T T T T T T #T T T T T T T T T T #T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T
Retry count exceeded; starting again
TFTP from server 192.168.1.102; our IP address is 192.168.1.110
Filename 'myroot.cramfs'.
Load address: 0x20008000
Loading: T T T #T T T T T T T T T T #T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T
Retry count exceeded; starting again
TFTP from server 192.168.1.102; our IP address is 192.168.1.110
Filename 'myroot.cramfs'.
Load address: 0x20008000
Loading: T T T T T T T T T T T #T T T T T T T T T T T T T T T #T T T T T T T T T T T T T T T T T #T T T T T T T T T T #T T T T T T T T T T #T T T T T T T T T T #T T T T T T T T T T #T T T T T T T T T T #T T T T T T T
Retry count exceeded; starting again
TFTP from server 192.168.1.102; our IP address is 192.168.1.110
Filename 'myroot.cramfs'.
Load address: 0x20008000
Loading: T T T T T T T T T T T T T T #T T T T T T T T T T #T T T T T T T T T T #T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T
Retry count exceeded; starting again
TFTP from server 192.168.1.102; our IP address is 192.168.1.110
Filename 'myroot.cramfs'.
Load address: 0x20008000
Loading: T T T #T T T T T T T T T T #T T T T T T T T T T #T T T T T T T T T T #T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T
Retry count exceeded; starting again
TFTP from server 192.168.1.102; our IP address is 192.168.1.110
Filename 'myroot.cramfs'.
Load address: 0x20008000
Loading: T T T #T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T
Retry count exceeded; starting again
TFTP from server 192.168.1.102; our IP address is 192.168.1.110
Filename 'myroot.cramfs'.
Load address: 0x20008000
Loading: T T
Abort

I've had the same problem. It works only if there is not much other traffic on the same ehternet interface you are booting from (ie separate ethernet interface). Also, a 10M hub inbetween helped a bit.
Actually, the U-Boot AT91 timer code is a buggy piece of crap and it gets a timeout too early. But this i've found later, when implementing NOR support for UBOOT for a custom board without ethernet. I have to port my patches later when I have free time back to eval board u-boot and check if there are some more bugs there.