I have been browsing the internet trouble-free for the past several days, but yesterday after I restarted, I could no longer access web pages through Internet Explorer. Mozilla Firefox is still working fine, but every page I attempt to visit with IE returns the standard "The page cannot be displayed" message with "Cannot find server or DNS Error" at the bottom. I updated SpyBot and ran a couple of scans, which found a few items, but that didn't fix the problem.

I urgently need to resolve this, since I'm a consultant working on-site and Firefox isn't compatible with the site(s) I'm working with.

Here's my Hijack This log:
Logfile of HijackThis v1.99.0
Scan saved at 9:46:29 AM, on 6/29/2005
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\ibmpmsvc.exe
C:\WINDOWS\System32\Ati2evxx.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\System32\svchost.exe
C:\WINDOWS\system32\spoolsv.exe
C:\Program Files\Dell\OpenManage\Client\ActionAgent.exe
C:\Program Files\Cisco Systems\VPN Client\cvpnd.exe
C:\PROGRA~1\NavNT\DefWatch.exe
C:\DMI\WIN32\bin\DellDmi.exe
C:\Program Files\Dell\OpenManage\Client\EventAgt.exe
C:\Program Files\Dell\OpenManage\Client\DLT.exe
C:\Program Files\Dell\OpenManage\Client\Iap.exe
C:\PROGRA~1\NavNT\Rtvscan.exe
C:\WINDOWS\System32\svchost.exe
C:\dmi\win32\bin\Win32sl.exe
C:\WINDOWS\SYSTEM32\Ati2evxx.exe
C:\WINDOWS\Explorer.EXE
C:\Program Files\Synaptics\SynTP\SynTPLpr.exe
C:\Program Files\Synaptics\SynTP\SynTPEnh.exe
C:\Program Files\Mozilla Firefox\firefox.exe
C:\Program Files\HijackThis\HijackThis.exe

R1 - HKCU\Software\Microsoft\Internet Connection Wizard,ShellNext = http://hostupdates.merc-int.com:81/?...012:59:57%20AM
R1 - HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings,ProxyServer = proxy:80
R3 - Default URLSearchHook is missing
O2 - BHO: (no name) - {53707962-6F74-2D53-2644-206D7942484F} - C:\PROGRA~1\SPYBOT~1\SDHelper.dll
O3 - Toolbar: &Radio - {8E718888-423F-11D2-876E-00A0C9082467} - C:\WINDOWS\System32\msdxm.ocx
O4 - HKLM\..\Run: [ATIModeChange] Ati2mdxx.exe
O4 - HKLM\..\Run: [SynTPLpr] C:\Program Files\Synaptics\SynTP\SynTPLpr.exe
O4 - HKLM\..\Run: [SynTPEnh] C:\Program Files\Synaptics\SynTP\SynTPEnh.exe
O4 - HKCU\..\Run: [SpybotSD TeaTimer] C:\Program Files\Spybot - Search & Destroy\TeaTimer.exe
O4 - Startup: Siebel QuickStart.lnk = C:\sea752\client\BIN\siebel.exe
O4 - Global Startup: Cisco Systems VPN Client.lnk = C:\Program Files\Cisco Systems\VPN Client\vpngui.exe
O8 - Extra context menu item: E&xport to Microsoft Excel - res://C:\PROGRA~1\MICROS~2\Office10\EXCEL.EXE/3000
O9 - Extra button: Start WebEx One-Click Meeting - {80947ADC-151D-490B-87F1-7C8CE1B46220} - C:\WINDOWS\DOWNLO~1\WebEx\324\atonecli.dll
O9 - Extra 'Tools' menuitem: Start WebEx One-Click Meeting - {80947ADC-151D-490B-87F1-7C8CE1B46220} - C:\WINDOWS\DOWNLO~1\WebEx\324\atonecli.dll
O15 - Trusted Zone: *.frame.crazywinnings.com
O15 - Trusted Zone: *.mercer.com
O15 - Trusted Zone: *.static.topconverting.com
O15 - Trusted Zone: *.windupdates.com
O15 - Trusted Zone: *.frame.crazywinnings.com (HKLM)
O15 - Trusted Zone: *.static.topconverting.com (HKLM)
O15 - Trusted Zone: *.windupdates.com (HKLM)
O15 - Trusted IP range: http://10.103.3.29
O15 - Trusted IP range: http://10.103.3.30
O16 - DPF: Acme -
O16 - DPF: Jacob - not available
O16 - DPF: KintanaClientCore -
O16 - DPF: KintanaClientProd -
O16 - DPF: KintanaCustom -
O16 - DPF: NinjaRMI - not available
O16 - DPF: RMI - not available
O16 - DPF: Swing - not available
O16 - DPF: {10F62CD7-6A94-4CA7-859C-E4E9D8BCCA2E} (Siebel Option Pack for IE 7.5.3) - http://micrm.merc-int.com/callcenter...OptionPack.cab
O16 - DPF: {15AD4789-CDB4-47E1-A9DA-992EE8E6BAD6} -
O16 - DPF: {253A9D23-F982-11D4-8BE4-00D0B7E61414} (SiebelHTMLApplication Class) - http://micrm.merc-int.com/callcenter...siebelhtml.cab
O16 - DPF: {3E68E405-C6DE-49FF-83AE-41EE9F4C36CE} (Office Update Installation Engine) -
O16 - DPF: {597C45C2-2D39-11D5-8D53-0050048383FE} (OPUCatalog Class) -
O16 - DPF: {59B625B2-27B9-4744-8C7C-E02D27DC4CC7} (Siebel Option Pack for IE 7.5.3) - http://micrm.merc-int.com/callcenter...OptionPack.cab
O16 - DPF: {6414512B-B978-451D-A0D8-FCFDF33E833C} (WUWebControl Class) -
O16 - DPF: {6706C0DA-2FA7-4FF5-8975-3CD44CC65E7E} (Siebel Option Pack for IE 7.5.3) - http://micrm.merc-int.com/callcenter...OptionPack.cab
O16 - DPF: {8AD9C840-044E-11D1-B3E9-00805F499D93} (Java Plug-in 1.3.1_13) -
O16 - DPF: {8F4F3368-54CA-4268-8225-0F4367472CF4} (MailClient Class) - http://micrm.merc-int.com/callcenter...MailClient.cab
O16 - DPF: {B38870E4-7ECB-40DA-8C6A-595F0A5519FF} (MsnMessengerSetupDownloadControl Class) -
O16 - DPF: {B9191F79-5613-4C76-AA2A-398534BB8999} - http://us.dl1.yimg.com/download.yaho...tocomplete.cab
O16 - DPF: {BAC01377-73DD-4796-854D-2A8997E3D68A} (Yahoo! Photos Easy Upload Tool Class) -
O16 - DPF: {CAFEEFAC-0013-0001-0001-ABCDEFFEDCBA} -
O16 - DPF: {CAFEEFAC-0014-0001-0007-ABCDEFFEDCBA} (Java Runtime Environment 1.4.1) -
O16 - DPF: {D27CDB6E-AE6D-11CF-96B8-444553540000} -
O16 - DPF: {E06E2E99-0AA1-11D4-ABA6-0060082AA75C} (GpcContainer Class) - https://merc-int.webex.com/client/v_...ck/ieatgpc.cab
O16 - DPF: {ED324F9E-715D-4BE2-B6DF-44FCB674AADF} (DDSC Class) - https://www.mercuryportal.com/psopor...ces/msddsc.cab
O23 - Service: ActionAgent - Dell Computer Corporation - C:\Program Files\Dell\OpenManage\Client\ActionAgent.exe
O23 - Service: Ati HotKey Poller - Unknown - C:\WINDOWS\System32\Ati2evxx.exe
O23 - Service: Cisco Systems, Inc. VPN Service - Cisco Systems, Inc. - C:\Program Files\Cisco Systems\VPN Client\cvpnd.exe
O23 - Service: DefWatch - Symantec Corporation - C:\PROGRA~1\NavNT\DefWatch.exe
O23 - Service: DellDmi - Dell Computer Corporation - C:\DMI\WIN32\bin\DellDmi.exe
O23 - Service: DEventAgent - Dell Computer Corporation - C:\Program Files\Dell\OpenManage\Client\EventAgt.exe
O23 - Service: DLT - Dell Computer Corporation - C:\Program Files\Dell\OpenManage\Client\DLT.exe
O23 - Service: Iap - Dell Computer Corporation - C:\Program Files\Dell\OpenManage\Client\Iap.exe
O23 - Service: IBM PM Service - Unknown - C:\WINDOWS\System32\ibmpmsvc.exe
O23 - Service: Symantec AntiVirus Client - Symantec Corporation - C:\PROGRA~1\NavNT\Rtvscan.exe
O23 - Service: NVIDIA Driver Helper Service - NVIDIA Corporation - C:\WINDOWS\System32\nvsvc32.exe
O23 - Service: OracleOraHome_817Agent - Oracle Corporation - C:\oracle\ora_817\bin\dbsnmp.exe
O23 - Service: OracleOraHome_817ClientCache - Unknown - C:\oracle\ora_817\BIN\ONRSD.EXE
O23 - Service: OracleOraHome_817DataGatherer - Oracle Corporation - C:\oracle\ora_817\bin\vppdc.exe
O23 - Service: OracleOraHome_817TNSListener - Unknown - C:\oracle\ora_817\BIN\TNSLSNR.exe
O23 - Service: OracleServiceORCL817 - Oracle Corporation - c:\oracle\ora_817\bin\ORACLE.EXE
O23 - Service: Mercury ITG v55 - Unknown - C:\ITG55\bin\ksvc.exe
O23 - Service: Win32Sl - Intel - C:\dmi\win32\bin\Win32sl.exe

Resolved:
Somehow the connections settings were changed, so internet explorer was trying to go through a proxy server (port 80). I definitely did not change this myself, but I was able to remove the proxy setting with no difficulty.