If your image is getting too big, you might get a CRC error when decompression of the load is happening.

You might get the following output from the COM port

## Booting image at 02000000 ...
Image Name: Linux-2.6.24-rc6-pika#32
Image Type: PowerPC Linux Kernel Image (gzip compressed)
Data Size: 1411036 Bytes = 1.3 MB
Load Address: 00400000
Entry Point: 00400688
Verifying Checksum ... OK
Uncompressing Kernel Image ... OK
## Loading RAMDisk Image at 02200000 ...
Image Name: PIKA Warp 1.0.0-197
Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
Data Size: 50604048 Bytes = 48.3 MB
Load Address: 00000000
Entry Point: 00000000
Verifying Checksum ... Bad Data CRC

To fix this, you will need to connect to the COM port and enter the uBoot session.

Once there you will need to change the "load_nand_ramdisk"

For example:
load_nand_ramdisk=nand read.jffs2 2200000 200000 2600000

where 2600000 is the size

then save it:
saveenv

reboot