Ok. This is the second day straight that I've worked on this. I'm working on my gf's laptop.
Context: WinXP sp1, IE 6. Zonealarm. Netgear wgr614 router, wg511 network card.
Connection works.
Ping to ip and name work.
Ping to gateway works.
Excellent/very good signal.
DNS is set to auto on all systems, DHCP auto on all systems. Wired computer doesn't appear to have the same issues. Router spoofing MAC addy from wired system.
WEP secured, key shared.
Network card shares IRQ 11 with Cardbus controller. No conflicts.
Again, no problems connecting (and surfing to an extent.)

Problem: Frequent "page cannot be displayed" errors: f5, refreshing and/or selecting the address then (ctrl-c > ctrl-o > ctrl-v >enter) works to load the page, usually in one attempt. Particular websites refuse to load easily eg. Hotmail.com, Cosmopolitan.com (used to test for functionality).
Unusually long load time for each new address.
Extremely long, ~1 minute, load for IE. If the IE button is clicked while windows is still loading the other startup programs it opens in a snap, but doesn't load a page because the wireless isn't connected. If it is clicked after windows has loaded all it's startup programs, it takes around a minute to load. Seems like a hijack right? Read on.

Solutions sought:
System was restored to a point before recent installs but there was no affect on the connection errors. Prior to any virus scans Sys restore was disabled. Scans all made in safe mode first and again in normal.
AVG Virus Scan - 3 entries found and removed.
Trojan Downloader Small.34.l wmplayer.exe.tmp,
Generic.Qg. cmeae05.dll,
Generic.QG. dppndw30104lib.dll.
TrojanHunter - No entries.
CWShredder - No entries.
Stinger from McAfee - no entries.
Spybot S&D - Several cookies, few minor items all cleaned, Alexa related.
Adware - Several cookies removed.
Hijackthis - only roughly 15 items, none suspicious.
cmd>tasklist: yeilds nothing that isn't in taskmanager.
Accessibility option: Tools>Internet options>'General' - Accessibility>uncheck custom Style sheet. No affect.
Third party browsing: Tools>Internet Options>Advanced>Uncheck "Enable third party browser extensions." No affect.

As I fell asleep working on this thing this morning a window opened on the computer that went to "www.weeklycashincome.com." I can't be certain that I didn't click a link for it cuz I was dozing off, although i didn't see one anywhere that I could've clicked. Again, sp1 so pop-ups aren't blocked. As I started this post a window came up for blogger.com. Appeared to be a legit page access as though I'd typed in www.blogger.com, but I didn't.
Again, I think it's a hijack, but I have been unable to find any evidence of such. I am almost 100% positive all my network settings are configured properly.

Some extraneous, possibly irrelevant facts. Recently, this laptop could connect to a public wep secured network, but couldn't browse the internet. The MAC address had been given direct access to the network as well, but no internet sites could be viewed. Also, several windows errors occured when setting WMP10 properties, closing/opening one or more IE windows, etc. It was severe enough to prompt a system restore.
Some help would be greatly appreciated. Thanks. Citizenchan. PEACE >

Given some of the background info you've posted, I'd suggest giving us a HijackThis log to review; we may catch something that you overlooked. If you do post, please post the log in a new thread in our Virues, Spyware, and other Nasties forum, not in this forum.

Also- if the machine is connected via Ethernet, does it exhibit any of the same symptoms?