Hello Ian- welcome!

2 things come to mind:

1. Check all of your computers for viruses and spyware/malware/adware; these programs can cause the connection problems you're experiencing. Read through some of the other threads in this forum for instructions for downloading, installing, and running the following (free) spyware removal utilities:

HijackThis
Ad Aware
SpyBot Search & Destroy
SpywareBlaster

2. Check your security-related settings in your Internet Options control panel.Make sure your security levels aren't too restrictive, that you don't have unwanted entries in your "Restricted Sites", etc. You can try lowering the security levels temporarily and see if that helps; if not, my bet would be that it's a spyware-related problem.

I tried the ad aware software including the hijackthis. below are the resulting log. pls help me with this... thnx so much

Logfile of HijackThis v1.97.7
Scan saved at 2:06:03 AM, on 4/22/2004
Platform: Windows XP SP1 (WinNT 5.01.2600)
MSIE: Internet Explorer v6.00 SP1 (6.00.2800.1106)
Running processes:
C:\WINDOWS\System32\smss.exe
C:\WINDOWS\system32\winlogon.exe
C:\WINDOWS\system32\services.exe
C:\WINDOWS\system32\lsass.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\System32\svchost.exe
C:\Program Files\Common Files\Symantec Shared\ccEvtMgr.exe
C:\WINDOWS\Explorer.EXE
C:\Program Files\Common Files\Symantec Shared\ccApp.exe
C:\Program Files\Internet Explorer\IEXPLORE.EXE
C:\WINDOWS\system32\spoolsv.exe
C:\Program Files\Norton SystemWorks\Norton AntiVirus\navapsvc.exe
C:\WINDOWS\System32\nvsvc32.exe
C:\Program Files\Analog Devices\SoundMAX\SMAgent.exe
C:\Program Files\Messenger\msmsgs.exe
C:\PROGRA~1\WINZIP\winzip32.exe
C:\Documents and Settings\station02\Local Settings\Temp\HijackThis.exe
R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Search Bar = http://red.clientapps.yahoo.com/cust...ch/search.html
R0 - HKLM\Software\Microsoft\Internet Explorer\Main,Start Page = http://red.clientapps.yahoo.com/cust...//my.yahoo.com
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Search Bar = http://red.clientapps.yahoo.com/cust...ch/search.html
R1 - HKCU\Software\Microsoft\Internet Explorer\SearchURL,(Default) = http://red.clientapps.yahoo.com/cust.../www.yahoo.com
O2 - BHO: (no name) - {02478D38-C3F9-4efb-9B51-7695ECA05670} - C:\Program Files\Yahoo!\Companion\Installs\cpn\ycomp5_3_12_0.dll
O2 - BHO: (no name) - {06849E9F-C8D7-4D59-B87D-784B7D6BE0B3} - C:\Program Files\Adobe\Acrobat 5.0\Reader\ActiveX\AcroIEHelper.ocx
O2 - BHO: (no name) - {BDF3E430-B101-42AD-A544-FADC6B084872} - C:\Program Files\Norton SystemWorks\Norton AntiVirus\NavShExt.dll
O3 - Toolbar: &Radio - {8E718888-423F-11D2-876E-00A0C9082467} - C:\WINDOWS\System32\msdxm.ocx
O3 - Toolbar: Norton AntiVirus - {42CDD1BF-3FFB-4238-8AD1-7859DF00B1D6} - C:\Program Files\Norton SystemWorks\Norton AntiVirus\NavShExt.dll
O3 - Toolbar: &Yahoo! Companion - {EF99BD32-C1FB-11D2-892F-0090271D4F88} - C:\Program Files\Yahoo!\Companion\Installs\cpn\ycomp5_3_12_0.dll
O4 - HKLM\..\Run: [NvCplDaemon] RUNDLL32.EXE C:\WINDOWS\System32\NvCpl.dll,NvStartup
O4 - HKLM\..\Run: [nwiz] nwiz.exe /install
O4 - HKLM\..\Run: [ccApp] C:\Program Files\Common Files\Symantec Shared\ccApp.exe
O4 - HKLM\..\Run: [ccRegVfy] C:\Program Files\Common Files\Symantec Shared\ccRegVfy.exe
O4 - HKLM\..\Run: [PC Link] X
O4 - HKLM\..\RunServices: [PC Start] X
O4 - Global Startup: Microsoft Office.lnk = C:\Program Files\Microsoft Office\Office10\OSA.EXE
O8 - Extra context menu item: E&xport to Microsoft Excel - res://C:\PROGRA~1\MICROS~2\Office10\EXCEL.EXE/3000
O8 - Extra context menu item: Yahoo! Dictionary - file:///C:\Program Files\Yahoo!\Common/ycdict.htm
O8 - Extra context menu item: Yahoo! Search - file:///C:\Program Files\Yahoo!\Common/ycsrch.htm
O9 - Extra button: Messenger (HKLM)
O9 - Extra 'Tools' menuitem: Yahoo! Messenger (HKLM)
O9 - Extra button: Related (HKLM)
O9 - Extra 'Tools' menuitem: Show &Related Links (HKLM)
O12 - Plugin for .spop: C:\Program Files\Internet Explorer\Plugins\NPDocBox.dll
O16 - DPF: {30528230-99F7-4BB4-88D8-FA1D4F56A2AB} (YInstStarter Class) - http://download.yahoo.com/dl/installs/yinst0401.cab
O16 - DPF: {A17E30C4-A9BA-11D4-8673-60DB54C10000} (YahooYMailTo Class) - http://us.dl1.yimg.com/download.yaho...ymmapi_416.dll
O17 - HKLM\System\CCS\Services\Tcpip\..\{2BADC702-8396-4DB3-8F6F-6F9073DB34FE}: NameServer = 192.168.0.1
O17 - HKLM\System\CS1\Services\Tcpip\..\{2BADC702-8396-4DB3-8F6F-6F9073DB34FE}: NameServer = 192.168.0.1
O17 - HKLM\System\CS2\Services\Tcpip\..\{2BADC702-8396-4DB3-8F6F-6F9073DB34FE}: NameServer = 192.168.0.1

OK, I'm not as much of an expert on all of the various malware programs out there as some of our other members are (I use Linux primarily, so I'm immune to this stuff ), but the log looks pretty clean to me except for all the Yahoo toolbar/serch/etc. crud.

Have you done a virus scan?
Have you run Ad Aware and SpyBot?
If so, what did they have to say?

Also- what about your security settings; have you checked those yet?