All the previous is good advice, I can think of one other strong possibility, and that is a "memory leak" and/or "deadly embrace"

The reason I say this is that you are running XP Pro, and you have CPU = 100% and RAM = 75%

If you look at your active jobs you should see something like "idle task" at the top of the list and using a hell of a lot of resource? If not, exactly what processes are using the CPU resource? XP has a built in processor cooling proggy (the idle task program), and you need not worry about it. If it is any other process(es) then that is where the problem lies.

The RAM value of 75% worries me. In Win98/98se and Me, the resource metering does not work. This is a known problem with those OSes and was never fixed. This problem does not exist in NT/2k/XP, so the 75% can be assumed to be genuine.

I would suggest that you get a memory management tool such as "Ram Idle Pro" or "Ram Booster" You should be able to get a free version or a trial. I am only suggesting that you use this as a DIAGNOSTIC TOOL, the answer to insufficient RAM is to buy more, unless you have a very old machine and the cost is not justified.

Boot up as normal, set the memory manager to run with a CPU usage of up to 85%, and force a RAM defragmentation. If this drops the RAM usage down to around 5%, keep using the machine and see if it remains at a reasonable level when you complete each task.

If the RAM usage drops and stays low when you are not actually running anything, then you have a "memory leak". This happens when one program tries to grab memory before another one has handed it back to the system. It frequently happens on boot up with fast machines, although it can happen when running certain applications together.

A "deadly embrace" occurs when two programs try to grab the same resources. This usually freezes the machine, but not always.

To sort it out you have to

1. Determine your essential processes from booting in safe mode
2. Boot normally and shut the processes down one by one until you find the culprit.

The issue can frequently be resolved by changing the boot sequence. The easiest way to do this is probably to uninstall and re-install the offending software, although security stuff will try to load itself first.

I will probably get flamed for this but this is my personal opinion and based on numerous incidents: Start by uninstalling Norton make sure you are not on the Net.......I have come across at least a dozen machines with problems that were Norton related. Then try a re-installation, and do not have it doing "background scanning".

You should only have one AV doing "interactive" scanning as well.

Just a few thoughts

Cheers