CPU usage stuck at 50%+ after file is transferred over network

strange issue just popped up. my system will run fine and my cpu usage will be normal until I send a file to another system on my home network. Once I do this, the CPU usage jumps to 50+. I have tried system restore, windows system file checker, degrag, 2 different virus scanners, 2 different adware programs, uninstalled-reinstalled all network gear, rebooted, reset router, uninstalled any unneeded programs, double-checked msconfig for unwanted items or services, and checked for unwanted processes or applications in the task manager. nothing seemed to help.
I played around for a few hours and then figured out ( i think) that the cpu doesnt jump until after i have sent a file over the network. it is at that point that it will get stuck at 50+. I also tested prime95; the cpu usage returned to normal once this was closed.
also, i recently stopped all overclocks on this system to ensure stability (see sig. for specs). I had run it oc'ed for a few months. if it means anything, i recently experienced two instances where the system would boot to the desktop and then crash unexpectedly. I dont believe this was a power outage as I have the system hooked up to a UPS.

Any ideas?
appreciate your help; thanks

just ran some more tests. it does indeed appear to be the file transfer that is causing the cpu usage to jump.
also, windows is up to date. have been running XP SP2 for about a month now.
thanks

oops, forgot to add.
wireless nic: dlink dwl-520 rev b. latest drivers.
router: dlink 624 (the super g one). latest firmware.
the other system is using an integrated 3com 10-100 nic

For some reason, transferring files over the network is pinning your CPU, but it appears that because you have an HT processor, it won't show as using more than 50% for that one task. The reason it goes over 50% is because other tasks are using small portions of your processor as normal.

First thing I would do is to connect your machine to your network with a wire instead of a wireless card if possible. Could be the wireless connection that is using all the CPU it can get to transfer files.

get a new nic card to test with or try it in another PCI slot.

which of your processes is using those 50% CPU?

the proc on the left is pegged at the top. after rebooting, i can use the system for 2 minutes or 20 and nothing out of the ordinary happens. as soon as i send a file, it jumps and stays even after the file has been sent.

I didn't ask which CPU is hogged, but which process hogs that CPU.

gotcha. like the culprit is:
WZCSLDR.exe
looks like this is the dlink service and has been known to cause excessive cpu activity.
anyone see this before?

i said to heck with it and just uninstalled all the dlink stuff. I can't use the "superG" or "turbo" modes and the file transfers arent as quick as they were at one point but... oh well, at least it works.