Slow Keyboard Response Time II

Original Question:
I just purchased a Dell Inspiron 1520 loaded with Windows XP.  I opted not to get Vista due to the bad reviews.  In any event, just recently my keyboard stopped responding quickly.  When I type there is a lag before the letters show up on the screen.  It is an intermittent problem.  When I first start typing it responds quickly but then it slows up.  I searched all over the internet and have tried numerous techniques to solve the problem with no luck.  When I called Dell they did some items and then let me know I would have to reinstall XP which I don't want to do yet without trying to solve the problem.  To date I have tried the following: 1) going to the control panel and changing repeat delay and repeat rate settings, uninstalling the keyboard.sys files and then reinstalling it, diabling IE plug-ins.  Nothing has worked.  Any hints out there??

Subsequent Steps to Resolve:
Hi when that happens, check task manager, for process that could be using processor and makes they keyboard to be slow.

in the process you should be procesor usage, look at process that uses to much processor.
or even better
hijackthis log should help us diagnose.
Hijackthis:
http://www.trendsecure.com/portal/en-US/tools/security_tools/hijackthis
Open Hijackthis, click "Do a system scan and save a logfile" please don't fix anything yet.
Please attach the logfile.

My opinion...
From your log, I notice that you are using several google tools. I can tell you now that each one of them alone is enough to slow your system down and even cause crashes. You show 3 listed...
Google Desktop Search
Google Toolbar
Google Updater
Of the 3, I would look seriously at Google Updater. However, my suggestion to you is that unless you really, really love them, then uninstall all 3. Each one has been known to crash and significantly slow down systems. All 3 together could really mess you up..
as I said... my opinion. Worst case... remove all of Google add-ons and reboot. See how it is. If still bad, you can always re-install.

The log seems clean.
Try This
Click start, run, type, msconfig, select selective start up uncheck all less load system services.
Reboot, and test the keyboard, if it works correctly, that means there is software affecting the keyboard.

O20 - AppInit_DLLs: C:\PROGRA~1\Google\GOOGLE~2\GOEC62~1.DLL
O23 - Service: GoogleDesktopManager - Google - C:\Program Files\Google\Google Desktop Search\GoogleDesktop.exe
O23 - Service: Google Updater Service (gusvc) - Google - C:\Program Files\Google\Common\Google Updater\GoogleUpdaterService.exe
Looks like Google Desktop search and Updater are still running.
click start > run
type in "msconfig"  (no quotes)
hit enter
select startup
look for anything Google and remove the checkmark to disable it from starting
select services
check the "hide all microsoft services" box
after the list updates, look for Google Updater Service and/or anything Google
remove checkmark to disable
exit out of msconfig, clicking on ok/apply as needed
reboot
you will get a message saying windows is starting in "selective startup" mode
means nothing... check box to tell it not to tell you again
see how the keyboard is now.

when this starts happening, do a ctrl-alt-del to open task manager. Click on CPU to sort by CPU percent. The highest should be at the top. Is there anything suddenly hogging the processor? Also, run another hijack this and take a look at it. Is all the google stuff, especially updater, now gone?
Another thing. Norton... MAJOR resource hog. This can cripple you if there is even the slightest problem with it. A recent update may have hosed you. Try disabling it temporarily to see how things work. Disconnect from the net while doing so if no other protection exists. Norton may be trying to communicate with it's update site and having trouble, thereby hanging the system.

My Question:
I am having the same problem.  I have found alot of people with the same problem and it may relate to the Dell Inspiron 15xx series (mine is a 1501).  The mouse tracks fine on the screen but keyboard input and mouse clicks seem to get delayed in the buffer from a second up to about 30 seconds.  It isn't like the machine is frozen, there is no hickup in the processor usage, mouse continues to function, video continues playing steadily.  Quitting every non-essential process doesn't correct the problem.  It comes and goes but seems to overall be getting worse.