NEED HELP! Modem keeps disconnecting w/K7T266 Pro & WinXP

Question

My system:
K7T266 Pro
Athlon 1333MH
256Mb DDR 2100
MSI GeForce 2 MX, 32Mb
Zoom V.92 internal modem
SB Live! 5.1
2 x 80Gb Maxtor HD
LiteOn 16x12x40 CD-RW
USB mouse
340 W Enlight Power Supply
This system worked fine on the internet when I was running Win98.  I upgraded to WinXP and now the modem keeps disconnecting shortly after connecting (but it always connects for a short period of time).
Here's what I have tried:  Reloaded WinXP Home Edition on a newly formatted HD using a clean install (not an upgrade) and the NT file system.  Loaded the latest MSI 4-in-1 drivers and upgraded Bios to latest version (v1.9).  Reloaded all the software.  Got all the latest XP drivers and WinXP updates.  Have tried 4 different brands of modems, internal and external.  Have tried modems in different PCI slots (currently using PCI slot 3 with SB in slot 4).  Have tried modem on different Com ports (currently using Com 3).  Have tried slowing down the com port speed.  There is no IRQ sharing with the modem.  Have tried different phone jacks and cords (the same ones that work fine on the older HP Win98 computer I am writing this on).  Have tried 2 different ISPs (currently using CompuServe).  Have reloaded the ISP software several times (trying different versions) and currently have their latest XP version - ISP says others are not having this problem with their software (have spent hours with their technical help with no resolution).  Not using any ad blocker or anti-virus software (yet).
Nothing I have tried has made any difference so far.  Am I missing something?  I don't want to go back to Win98!
Oh ya, another minor annoyance:  My system freezes after sitting idle for a while, even though the Windows power scheme is set to Always On and no screensaver.  Otherwise, everything else works fine.

Answer 1

Hello everyone,
I was gone for a few days, but when I got home I was very happy to see some more posts to this thread!!
Last night I tried disabling the SoundBlaster (with the Windows System Device Manager).  I disabled both the sound card and the game port.  The modem was still disconnecting.
Until now I hadn't heard of Via chipsets and SoundBlasters not getting along well with each other either.  I had, however, previously tried another sound card - it was an older Diamond Monster card I had, but I couldn't find a WinXP driver for it.  It didn't work well at all with WinXP.  So back to the SoundBlaster Live! 5.1.
I did find a cure for the other problem I mentioned.  I noticed that the SoundBlaster and all 3 USB controllers were sharing IRQ 10.  I removed the USB optical mouse and tried a PS2 ball mouse.  That solved the problem where the system was freezing after sitting idle for a while.  I sure liked the optical mouse better though.  This same problem may have been related to another one I noticed.  When playing audio CDs, sometimes the sound would stop momentarily and then go on again.  I haven't yet had a chance to see if removing the USB mouse solved that problem as well.  I have also noticed that the volume of audio CDs are controlled by the wave volume and not the CD volume.  Is this normal?  I have both the analog and digital cables connected and the CD digital setting enabled.  It's very annoying, since turning the volume up on audio CDs causes the Windows wave sounds to blast me out when they play.  I don't know how to set the SoundBlaster to use one of the other unused IRQs - can anyone tell me how to?
I haven't yet tried the PCI latency patches, because I wasn't too hopeful after seeing that it didn't work for Philipponnat.
Now for the Bios.  I have always had my Primary Graphics Adapter setting on AGP.  The onboard modem and audio settings have always been set to disabled.  I was excited to see that Philipponnat found a cure for the modem disconnections with the PCI latency setting.  When I went to my computer to do the same thing, I was disapointed to find that my Bios does not have a setting by that name, either in the PNP/PCI configuration or anywhere else.  The only thing I found that looked related was one called "PCI Delay Transaction" in the Advanced Chipset Features section, but the only settings available are enabled or disabled.  Mine was set to disabled, but I couldn't tell any difference when I set it to enabled.  Maybe we have different boards - mine is version 1, but I have flashed the Bios to the latest version I found, v1.9.
I have noticed another strange thing in the Bios.  The Bios no longer detects the power supply fan speed - it always reads zero RPM in Bios even though the lead is hooked up.  The other fans show a reading.  The power supply fan used to show a reading when I first put the computer together.
I also have S.M.A.R.T. enabled.  I have 2 identical hard drives.  They are Maxtor 80Gb 7200RPM ATA133 drives which are S.M.A.R.T. capable.  Only the primary drive (master on the primary IDE) displays S.M.A.R.T values in SpeedFan.  The other drive is set as a slave on the secondary IDE (my CD-R-RW is set as the master on the secondary IDE).
There have sure been a lot of wierd things about this motherboard.  Thank you everyone for your input so far.  Still need more help!!
John