SDRAM Frequency

[jgis19]

I don't know if this is the right post for this question but I will ask anyway.
I built a new system as follows,
ECS P4VXASD2+ MB
Intel P4 2gz cpu
Atec 300watt PSU
512 mb pc 133 RAM 2 sticks
This week I decided to upgrade too 2 sticks of 512 mb of pc 2100 RAM. The problem being when I set the frequency to 133mz in BIOS the system has numerous boot errors and goes back to post or if it does go back to Windows XP Home Edition it will crash there giving me a bosd saying memory error.The system seems to work fine with BIOS set to 100mhz frequency.
All of the jumpers are set per the ECS manual and the sticks are in the right slots. Am I missing something here?
As an aside, sometimes but not every time when I am on the NET and click to open a new page, the system will shut down and reboot itself?
I am confused.
Thanks

 

[upec]

Maybe the memory timing setting is too agressive. I would change it to a slower setting.