P4 network performance SUCKS!!!- HELP

I've got a problem with a customer. They just bought a Gatway P4 with 850 chipset 256MB RAM, 20GB ATA100 HDD, 3C905cTX NIC. The network is a Windows NT 4.0 SP5 TCP/IP network with about 10 clients running WinProxy. 3Com Office Connect Dual Speed Hub.
Now that I've got that out of the way...

The network is running fine on all of the other computers PII 266 to PII 400's but on the P4 system the network performance SUCKS big time! I've tried about everything that I know of. I've renamed config.sys and autoexec.bat, I've ran msconfig and removed almost everything from the start up, I've removed the FindFast from the startup group and the network performance still crawls. They called Gateway and Gateway just sent them another system but we get the same performance issue. They run an application that connects to a data base on the NT server and this is their MOST used application. The application loads really fast, but when transfering data from the "S:" drive it slows down to about the speed of reading off of a floppy drive! (It will connect to the server and all drive mappings really fast)

I've changed the settings for the NIC to 10/half, 10/full, 100/half, 100/full, auto sense and hardware default...it doesn't help at all. I've removed all protocols except for TCP/IP still running slow. The NIC is a 3com 905CTX card. I'm about to point fingers at the NIC but would like imput from you guys also.
Any suggestions????

JKS

Well, since you just got this computer and THEN got another brand new to replace it, I think hardware failure is unlikely. Since the other computers all work, we know that the server and router is configured properly. Since it connects to the server and drive mappings, we know that it's not basic TCP/IP configuration. That leaves only advanced TCP/IP configuration, browser functions, and broadcast storms.

I think the most likely cause is browser functions (my personal specialty <IMG SRC="smilies/smile.gif" border="0">). Read this article to find out more about browsing and how to disable a possibly conflicting setting.

As for broadcast storms, disable NETBIOS on this computer and add the servers IP to the LMHOSTS file, then delete that mapped network drive, as well as any shortcuts to shares on that computer, then reboot and try to connect.

Advanced TCP/IP configuration involves editing the TCP/IP key in the registry. Microsoft has included a listing of all valid registry keys in the Server resource kit called regentry.chm. Look around in there to double that all setting match the older computers.

Thanks for the article. I should have mentioned that this one computer (P4) is running Win98SE. I will still try out what you suggested.
This is why I wanted more imput, I ALWAYS learn something new from my friends at Windrivers.

Well, there is a slight difference in Windows 98.

To disable browser function, in the network properties, click on Client for Microsoft Networks, make sure that Browse Master is disabled on the Win98 computer. Here is a page on NT netbios. If that page doesn't answer your question, look around on the site. It has almost everything you ever wanted to know about windows networkings.