One PC cannot connect normally to Internet

Hello,

I have no usual Internet connection on 1 Dell desktop XP Media Center Edition, with service pack 3.
By that is meant IE cannot connect and in AOL no internet but email works (send and receive)
I have two other PCs (laptop and desktop that can connect with either Ethernet or wireless but this one won't. The others run XP Pro and Vista.
The light blinks on the Linksys wireless adapter From systray says I am connected with 4 bars
The light stays on when connected to Eternet/Lan from systray says I am connected via LAN
MY ISP is Cox and I connect to them through a Cable modem. Cable TV works fine if that is needed.
The router is in the same room not 15 feet from the PC with issues.

this PC has worked OK for years and just stopped for reasons I cannot figure out.
I have tried reseting connections, booting, resetting IE8 per microsoft.
I also went backwards by 2 months in Restore to no avail.
Removed and reloaded AOL, etc
Have turned the Trend Micro firewall on and off with no difference, also changed settings still nothing
Been fighting this for a couple of weeks

Please note that on some level it does connects.
As Windows has updated itself,
AOL has no Internet (shows as blank) but can send and receive emails but Outlook and Live mail cannot...

My thanks to everyone in advance for their time/efforts

Yours sincerely,

RJ