Vista - IE7 & Firefox Stopped working as if no Internet Connection

Hey we have the same problem but I can connect to internet for 1-2 hours. Here's my story.

I can't browse the internet after 1-2 hours after windows startup but I can ping any sites using the command prompt, play any online games, download using my utorrent and update my antivirus. This problem occur last Wednesday I think. Tried to disable then enable again in the network connection but didn't work. The only way to browse again is to restart which is crazy.

Tried:
1) Reinstalling my network driver.
2) Scan for viruses and spywares.
3) Update using windows update
4) Reinstall OS then update again using windows update

Now I reinstall again my OS but didn't update using windows update yet(disabled it). I think the update this month is the culprit but I'm not pretty sure. Right now I don't have any problem with the internet. Anyone here can help me figure out what's the problem?

System:
Core 2 Quad 2.4Ghz
2GB DDR2 800 RAM
Seagate 250 GB SATA HD
8800 GT
Gigabyte GA-G31M-S2L (I'm using the built-in lan here)
Windows Vista Ultimate SP1 32bit

hey merk, tell me in a couble of weeks if it still work well, i'm almost sure that this problem come from an update. well... we'll see!

if it still works well, i will format again but w/o updates for a while

good luck

Oh crap! I lost internet again in firefox but can connect to IE. LOL. Now I'm lost. I'm tired solving this.

Do you the same problem tegowner?

aw damn! u didnt had the updates right?? yes i have the same problem, sometimes internet explorer crash in first, then firefox crash, or firefox crash in first, then internet explorer... but limewire browser works ALL the time.

For all the other things that use internet, everything is fine. I can still play Counter strike source :-P

Yeah no windows update. Maybe my firefox just crash or something happen weird or supernatural. LOL. Now, I don't know what to do next. Maybe go back to XP but I love Vista.

My OS is fresh. Installed Company of heroes OP, Left 4 Dead, Crysis Warhead, Firefox, NOD32, Zonealarm, Yahoo Messenger, Garena, uTorrent, xfire, registry mechanic, daemon tools, Nvidia 180.84 with Physx 8.10.13, Winrar, Realtek Lan and Audio driver.

up, sometimes, internet explorer stop working, but after ... i dunno, maybe 15 min, it works again, then it dies again... and i have the same programs running in process list