Hi, presto. One of the less-obvious reasons for "stalled" webpages or "stalled" downloads is packet-loss from your ISP. NIS filters damaged packets, because these are known to cause problems. Thusly, NIS may be bringing-to-the-surface a problem you had before, but didn't know about. This would also show up as intermittent corruption in downloaded files from the days before you installed NIS. If you had to download something 2 or 3 times before you got a download that worked properly - this is a really good indicator of the problem.
Here are a few things you can try to see if you can isolate the problem to your own equipment and/or software:
1. Are you running wireless? If so, try running wired. If you can run wired reliably but have intermittent problems when running wireless - the radio in your router may be corrupting wireless packets. This is a known problem with some cheaper routers when they overheat. Is your router out in the open air where it can be properly cooled by room air, or is it hidden away on a recessed shelf in a cabinet where it eventually cooks in its own juices?
2. A Firmware update for your Router may be required to fix bugs in the router. Check with your router manufacturer to see if something is required there.
3. What does Toshiba have to say about your problem? Do they have BIOS updates or driver updates for your Laptop to address compatibility or reliability issues?
4. Buggy wired network drivers in your machine can cause a similar situation to problems described above - if the drivers react poorly to corrupted packets or a fast network stream. Are there updated network drivers for your particular network card direct from the network card manufacturer? If so, get the update from the manufacturer's website and follow their instructions to update your network drivers to a newer version than what is available from Toshiba.
5. A similar situation can occur as in item 4 - but with wireless network drivers rather than wired network drivers. The solution is similar as well. Go to the wireless card manufacturer's website and download the latest-'n-greatest driver updates - then follow their instructions to update your wireless network drivers.
Here are some things that you can try to determine whether the problem is not you - but your connection to the Internet:
1. Does the problem get worse in the evening when there are lots of people online - and then lessen or disappear if you are working at 3:00AM in the morning? If so, this is a classic case of ISP router overload causing packet loss. The router at the ISP which is causing the problem will have to be upgraded.
If you know someone with a competitor's ISP - and their machine is working reliably - you can try connecting at their place. If your problem vanishes at their place - you've got a powerful indication the problem is with your ISP.
Note: You mentioned your friend next door is having the same problem as you. If both of you are on the same ISP - you have a powerful indication it's not your machine's problem. Rather, it's an overloaded node on your ISP's equipment serving your particular neighbourhood. (IOW, the guys across town may be fine on your ISP because their particular node's equipment is not overloaded with customers. You may be not so fortunate.)
2. Does the problem go away when you use https:// (IOW, a secure encrypted page)? If so, this is another way to prove the problem is packet loss - because an encrypted page will resend corrupted packets that fail the security validation - where normal webpages may just ignore you (your connection "falls off the face of the earth" and you sit there forever watching the spinner).
There. That ought to keep you busy for a while. 
Please let us know how you make out. That feedback will be especially useful if something on that list turns out to be the fix for your problem.