The system is XP Home, Athlon XP2400, 2x40GB HDD, 2x512MB RAM, Radeon 9550 Video Card, onboard sound and NIC.

In the absence of:

1)   Malware, spyware, viruses of any type
2)   Operating temperatures outside acceptable limits
3)   Unnecessary system processes running in task manager
4)   A fragmented hard drive
5)   Faulty memory
6)   Any error messages or alerts

.....can anybody suggest what would cause a system to suddenly start taking 30 seconds or longer to load any selected application?

The only unaffected program, curiously, is Internet Explorer. The only recent change to the system is the installation of a store BOUGHT version of Counter Strike.

I'm open to suggestions....  Disconnect from the net then TRY it again.  Thanks, Fed. No effect.  

By the way, a free box of doughnuts to anyone who can change the   to a  .Check your CPU usage at the bottom of your Windows Task Manager screen.
What % does it say?With only this page open, it's fluctuating between 1 and 3%.

I'm starting to think my hard drive is trying to tell me something.   Maybe, have you tried one of those HD testing thingies?No. What is it?Manufacturers HD diagnostic. But first, dump the contents of prefetch folder and make sure indexing service is DISABLED.Emptied prefetch, and indexing service is already disabled. Still no change.  

Used Windows to check the disk, and it came up negative.  

I'm going to test the RAM again by physically removing each bank, and I'll try the HDD diagnostic. If that doesn't do it, I'll reinstall the OS. If that doesn't work, I don't see any other solution besides wiping the drive clean and starting over.  The hard drive diagnostic found corrupted sectors, and repaired them. The system is happy again.

Fed and 2K, these are for you:




And so is this:

Sometimes just kicking ideas around is enough.
Good result DOOFUS.  Replace the Hard Disk Drive.

Might damage even further if you keep it in use.

And don't think I am bloody coming back!YIKES! OMG !