I'm having a problem getting my PC running at the proper speeds.

PC Specs:

Mobo: ECS L7S7A2 Mobo
Proc: AMD 2500+ Barton
RAM: Dane-Elec 184 Pin 512MB DDR PC-3200
HD: 80GB WD Maindrive & 60GB Seagate Slave
Video: GeForce 2 MX400 PCI card
Sound: Soundblaster Live (onboard sound disabled in BIOS)
NIC: Kingston KNE-100TX (onboard NIC disabled in Device Manager)
400 Watt Powersupply

I purchased the mobo & processor about 2 months ago but was running
the proc as a 1900+ since I only had PC-2100 RAM. If I tried to bump
the FSB up to 166mhz my pc would freeze up on me.

This weekend I finally got the PC-3200 Ram and tried again to run the
FSB at 166mhz and my PC still locks up. It will boot into WinXP but as
soon as I attempt to launch an application (or let it sit for a few
minutes) it freezes up on me. Converting back to running as a 1900+
and my PC runs just fine.

Are there other BIOS settings I need to adjust in order for my PC to
be stable and running as a 2500+? I never did peel off the fan and
heatsink so now I'm worried I got scammed 2 months ago and they may
have sent the wrong processor? I'm really hoping it's something else
entirely and I don't have to deal with trying to get a 2 month old
part replacement...

Thanks for any advice.

Check the FID JP1 jumper (between the CPU socket & the printer port)...make sure it's set to either "by CPU", or to 11.0 for your 2500+

Your prob may be caused by your PCI video card...I ran across this, but I'm not sure what the "MC82" setting is that was mentioned:

http://www.ocworkbench.com/ocwb/ultimatebb.php?ubb=get_topic;f=35;t=004203

Here's a review on your board:

http://www.ocworkbench.com/2003/ecs/l7s7a2/l7s7a2-1.htm