Frequent ftp and browser page/file corruption

I'm just wondering if anyone can shed any light on my issue. I've had it once before, when trying to do the same thing (OK, I know, "don't do it then", but it's nothing unusual.)

Symptoms:

• Frequent failures to load pages in Firefox and (to a lesser extent it seems) IE:
  
  • Just get a blank page, or it never stops trying to load.
  • Graphics don't load or look corrupted (image offset half way through, or unfinished).
  • Get a page of code instead of it being rendered.
  • Various error messages, all of which relate to bad data coming in.
  
  
• Files corrupted/truncated both ways when FTP'ing to my hosting provider; no error messages!
• This does not happen to every file or website. Often, things will seem fine for a few minutes, then I get another bad image or page. FTP transfers seem to get truncated mostly, about 1 in 5 times.

What I did that seems to trigger the problem:

• Installed a second NIC, turned of all network services in its network properties to stop Windows constantly sending unwanted stuff through it.
• Installed Wireshark and winpcap, to use the new port as a dedicated monitor port in my Cisco lab.
• This, by the way, works perfectly. A nice, quiet monitor port that captured everything coming in.

After doing the above, I gradually start noticing the symptoms. The second time, I bought a new Realtek NIC instead of using a server NIC, thinking the drivers I had to faff about with on that NIC were probably the cause. Nope, it still happens. The PC had had a complete wipe and reinstall between the two times.

I've tried resetting winsock and tcp, and reinstalling the latest NIC drivers. I even reinstalled my browsers. Nothing made any difference. I also restored the default settings for the NIC (in network properties) as if I hed never changed anything. Still no difference.

Only a roll-back to before I installed the card and wireshark helped this time, at least so far (it's only been about ten minutes but I haven't noticed the problems yet). Last time I just wiped the OS.


So... anyone seen anything like this before? I really want to be able to use my monitor port for labbing.

Just guessing what you can try:
- Perhaps loading defaults in BIOS.
- Did you try with a functional NIC? Enable whatever services were disabled.

I've not changed anything (I don't think) in the BIOS but I'll take a look.

Yes, I tried reinstating the functions I unticked for the NIC. The problem remained.

When I get chance, I'll try stepping though things slowly (like a day or two for each change), and see if I can catch exactly what it is causing the issue. I was just hoping someone else had seen it to save me the time.

The first time it happened I was using a dual Intel PCI-E server NIC, with one port VLAN'd out for four VMWare guests onto my lab and the other as the monitor port. I thought I might have made things too complicated or that the driver for the card (there really wasn't one for Windows 7 as such) didn't quite work. It all seemed OK apart from starting to notice the problems I mentioned.

Oh by the way, I'm not using the additional NIC for my LAN connection, just for the monitor port. Obviously though something is affecting all connections in some way. It seems as if TCP is failing, given the errors and truncated files.

Try loading defaults in BIOS (clear CMOS) even though you haven't changed anything. It is not all about what you have changed. All hardware has some impact. I am not that of an hardware person to describe all that may be happening but here is a simple explanation:

Why did resetting CMOS fix my computer [Solved] - Fan - Motherboards

The BIOS performs the following...

1.Check the CMOS Setup for custom settings
2.Load the interrupt handlers and device drivers
3.Initialize registers and power management
4.Perform the power-on self-test (POST)
5.Display system settings
6.Determine which devices are bootable
7.Initiate the bootstrap sequence

The CMOS battery saves any changes to the BIOS defaults by supplying a constant voltage. Once that voltage is removed, the BIOS gets set back to factory defaults.

Your BIOS was probably getting stuck on loading bad drivers or it was erroring out on the POST and the computer wasn't booting to prevent your components from killing themselves.

I'll give the BIOS reset a go later tonight. It's worth a shot.

The roll back (after removing the new NIC to be extra sure) seems to have stopped the problem though. I've not noticed any of the issues since I did that this morning, so it definitely seems related to something software-related in those few steps that I'm doing.

I found the issue (most likely) so I'm updatng my post in case anyone else ever has the issue.

Looks like it was caused by MSE (Microsoft Secuirty Essentials).

After a few rollbacks and reinstalls and trying something else, only to have the problem reappear, I removed MSE and tried again. No network problems after that. So now I'm in the market for an new AV.

Normally MSE is the behaving AV even if not the best, keep us updated after finding your new one.

That's what I thought, and is why I've always used MSE even though it is not the best. I don't like overly-intrusive or troublesome AV.

I'm reasonably certain that MSE was the cause. Certainly the only change after the last roll-back was removing MSE. The problem has not occured since.

I've been trying Avira (free version) but have just uninstalled that because of the annoying pop-up advertisements from Avira! I know I could get rid of them by paying, but I don't like that sort of extortion from a company.

The search for an AV continues... in the meantime I'll simply use the best AV known; Common Sense ;-)