Here is the symptom which we found below:
1,The panic will happen when the memory plugged with 256GB after OS installation.
2,The system can boot normally if we un-plugged 2 memory riser (64GB). The total memory size is 192GB.
3,The system can boot normally with 256GB memory if we installed OS with 128GB memory first then upgrade the memory size to 256GB.
By the way, both ESXi 4.0 U1/4.1 RC can install and boot normally.
We only saw the kernel panic issue on both ESX 4.0 U1/4.1 RC version when conpleted the OS installation then booting the OS.
The attached is the table of the issue symptom.