Internet connection lost on data transfer

[PerXX]

Hey guys and gals,

I've got a majorly strange issue I've never experienced before.
I've recently started in a new company, who have some issues with their laptops internet connection.
Often, they will completely lose any internet connection, when 'stressing' the connection. The level of stress seem to differ - for instance, one reports even accessing network drives via the Ethernet will cause the failure (While using the Wireless is fine). In case of my own computer, normal use is fine, even downloading large files. However, starting up a Torrent program will with 100% accuracy shut down my network within 10 sec. This is the same, both via Ethernet or Wireless
Once the connection is lost, the only way to restore it is to disable & enable the Ethernet / Wireless interface. Sometimes even a full reboot is required.

These issues only appear to happen with Lenovo Thinkpad W510 and W520's. I've tested a W500 and was unable to replicate the program on that one.
I've tried connecting to various switches, including one in the DMZ, and the main switch located directly behind the Firewall, all providing the same result - loading up the Torrent program will shut down the interface.
It sounds like an issue with those specific models, however I've been informed that laptops that fail at work will function perfectly well when brought home, doing the very same tasks.
I'll be testing this myself when I get home today.

Have anyone heard about something similar, or got any suggestions as to where I should be troubleshooting?

UPDATE: I've now tested the laptop at home, and as I was informed, it works flawlessly. No issue at all running the torrent program, or other heavy downloads.

[PerXX]

No one with any suggestions or ideas?
Is there any information I could add that would help find the cause?

[Ishan]

If internet works fine while using torrents at home at those very same laptops but not at your office then it could be that the problems resides not in the laptops themselves but the routers in your office.

To me it looks like your routers are crashing:
1) Their firmware is bugged, can't take the stress as torrent clients do burden our network setup quite very much.
2) Overheating due to stress causes them to reset themselves.
3) Some routers can't handle UPnP very well.

My advice would be search the model no. that the router has and see if their is a remedy for such abnormal behaviour on some computer forums.

[PerXX]

Yeah, I agree it must be with the office systems. It's strange that it only seem to happen to some models of ThinkPad's.
As far as I understand, its not the switches resetting. When it happens it only affect that one laptop, not the network in general.
The error doesn't only happen due to using torrent clients. Often it happens during normal use. The torrent is simply something I use for testing purpose, because that has a 100% chance of causing the fail.

To briefly explain the network setup, we have a Sonicwall firewall, connected to a 3com 4400 Switch, which serve as our Main Switch. To this Main Switch we have two department switches (3com5500G and Intel Express 410T), as well as a "DMZ" & Customer switch (3com 3300).