Mostly, my downloading speed hangs in around 4 Mbps.  Occasionally, the speed drops to the high 3000s.  On a few occasions, the speed has droped to around 1500 to 2500 Kbps.  Once or twice in the last few months, the network has been down -- once for perhaps 20 minutes and once for several hours.

However, when I first signed on with Adelphia back in late March, I had severe speed problems even after rebuilding my hard drive.  Tier-one and Tier-two Adelphia service people were no help at all and sometimes told me far-fetched stories.  On one occasion, an Adelphia Tier-two analyst was down right nasty.  Tier-three people (probably system engineers) don't talk to the two lower tiers nor customers.  I finally wrote an e-mail to Adelphia management (via online help) describing my situation and threatening to complain to the FCC.  A couple days later, my speeds increased to about advertised speeds and have generally remained there ever since.  Good luck my friend...

I found out exactly what was happening now.  It was the Protowall causing my speed drop.  But I found a way that I can continue to use it without any problems.  I changed from the default Realtek 8139 NIC card in the computer to a Linksys NC100 NIC, which is one of the preferred cards to be used with Protowall.  Even the Protowall manual states that the Realtek 8139's are incompatible with the program and the driver which installs as a service on the Local Area Connection.  So if you are using the same program, you may be noticing the same drop in speed that I was noticing.

I'm having sort of the same problem you are, except pages take 30-45 seconds to load (using I.E. and Opera).  I ran speed tests a couple minutes ago:

::::::::::.. Download Stats ..::::::::::
Connection is:: 5427 Kbps about 5.4 Mbps (tested with 2992 kB)
Download Speed is:: 662 kB/s
Tested From:: http://testmy.net/ (server2)
Test Time:: Sat Jan 14 10:43:10 PST 2006
Bottom Line:: 97X faster than 56K 1MB download in 1.55 sec
Diagnosis: Awesome! 20% + : 60.56 % faster than the average for host (adelphia.net)
Validation Link:: http://testmy.net/stats/id-ZD7N6E8FI

::::::::::.. Upload Stats ..::::::::::
Connection is:: 249 Kbps about 0.2 Mbps (tested with 2992 kB)
Upload Speed is:: 30 kB/s
Tested From:: http://testmy.net/ (server2)
Test Time:: Sat Jan 14 10:45:23 PST 2006
Bottom Line:: 4X faster than 56K 1MB upload in 34.13 sec
Diagnosis: May need help : running at only 54.49 % of your hosts average (adelphia.net)

I just reinstalled windows and haven't messed with cablenut so I can understand why I'm not getting the usual 6.5mbit, but what the heck is with that upload?  It's been like that since I woke up this morning.

Although the slow upload is annoying, I will admit this is the first problem with HSI I've had in the past 7-8 months.

Logfile of HijackThis v1.99.1
Scan saved at 2:50:19 PM, on 1/14/2006
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:\WINDOWS\system32\spoolsv.exe
C:\WINDOWS\Explorer.EXE
C:\WINDOWS\System32\RUNDLL32.EXE
C:\Program Files\Creative\SBLive\Diagnostics\diagent.exe
C:\WINDOWS\System32\nvsvc32.exe
C:\WINDOWS\system32\winlogon.exe
C:\Program Files\No-IP\DUC20.exe
C:\Program Files\FlashFXP\flashfxp.exe
C:\Program Files\G6 FTP Server\G6FTPSrv.exe
C:\Program Files\Opera7\opera.exe
C:\Program Files\HijackThis\HijackThis.exe

O3 - Toolbar: &Radio - {8E718888-423F-11D2-876E-00A0C9082467} - C:\WINDOWS\System32\msdxm.ocx
O4 - HKLM\..\Run: [PtiuPbmd] Rundll32.exe ptipbm.dll,SetWriteBack
O4 - HKLM\..\Run: [NvCplDaemon] RUNDLL32.EXE C:\WINDOWS\System32\NvCpl.dll,NvStartup
O4 - HKLM\..\Run: [nwiz] nwiz.exe /install
O4 - HKLM\..\Run: [UpdReg] C:\WINDOWS\UpdReg.EXE
O4 - HKLM\..\Run: [diagent] "C:\Program Files\Creative\SBLive\Diagnostics\diagent.exe" startup
O4 - HKLM\..\Run: [SunJavaUpdateSched] C:\Program Files\Java\j2re1.4.2_06\bin\jusched.exe
O4 - HKCU\..\Run: [NvMediaCenter] RUNDLL32.EXE C:\WINDOWS\System32\NVMCTRAY.DLL,NvTaskbarInit
O9 - Extra button: (no name) - {08B0E5C0-4FCB-11CF-AAA5-00401C608501} - C:\Program Files\Java\j2re1.4.2_06\bin\npjpi142_06.dll
O9 - Extra 'Tools' menuitem: Sun Java Console - {08B0E5C0-4FCB-11CF-AAA5-00401C608501} - C:\Program Files\Java\j2re1.4.2_06\bin\npjpi142_06.dll
O9 - Extra button: Related - {c95fe080-8f5d-11d2-a20b-00aa003c157a} - C:\WINDOWS\web\related.htm
O9 - Extra 'Tools' menuitem: Show &Related Links - {c95fe080-8f5d-11d2-a20b-00aa003c157a} - C:\WINDOWS\web\related.htm
O9 - Extra button: Messenger - {FB5F1910-F110-11d2-BB9E-00C04F795683} - C:\Program Files\Messenger\MSMSGS.EXE
O9 - Extra 'Tools' menuitem: Windows Messenger - {FB5F1910-F110-11d2-BB9E-00C04F795683} - C:\Program Files\Messenger\MSMSGS.EXE
O16 - DPF: {01010200-5E80-11D8-9E86-0007E96C65AE} (SupportSoft Installer) - http://supportcenter.adelphia.net/sdccommon/download/tgctlins.cab
O16 - DPF: {0E5F0222-96B9-11D3-8997-00104BD12D94} (PCPitstop Utility) - http://www.pcpitstop.com/pcpitstop/PCPitStop.CAB
O16 - DPF: {6414512B-B978-451D-A0D8-FCFDF33E833C} (WUWebControl Class) - http://update.microsoft.com/windowsupdate/v6/V5Controls/en/x86/client/wuweb_site.cab?1136875584281
O16 - DPF: {C77FB8C0-8B6D-440E-AC26-2BD39E97E8F2} (SpdTCtl Class) - http://speedtest.adelphia.net/customerdiag/speedtest/SPEEDTESTACTIVEX.CAB
O18 - Protocol: msnim - {828030A1-22C1-4009-854F-8E305202313F} - "C:\PROGRA~1\MSNMES~1\msgrapp.dll" (file missing)
O23 - Service: NVIDIA Display Driver Service (NVSvc) - NVIDIA Corporation - C:\WINDOWS\System32\nvsvc32.exe

Yeah, my upload speeds are back to where they're supposed to be today.  Guess my node was really busy yesterday.