Taskbar freezing, CPU use at 100%.. please help

Where to start..

I have just returned home from a month long trip and since
I had left, my laptop has not been in use. When I return,
it functions just as it did before I left. During my time
away, my household's DSL modem suffered a short circuit
and had to be replaced. I have a wireless usb based
connection to the DSL modem and while the other computers
in my home did not have have any problems connecting via
the new modem, I did.

My CD drive is a little screwed up on the hardware side,
so to access the installation file for my wireless adapter
I opened the setup file on the CD. I managed to reinstall
the adapter and it recognized the connection.

I had to reboot my computer and when I did, my taskbar
froze up immediately. It freezes as soon as it loads,
sometimes it will unfreeze in and hour and sometimes it
remains frozen. I checked taskmanager and even though I am
not running any program, the CPU useage is at 100%. All
other programs work fine, slow, but they work.

Is there anyway to fix this problem without losing the
files in my hard drive? It it a laptop with only one
drive, I do not have access to a burner or external usb
drive and AOL still refuses to connect to the internet.

My operating system is Windows XP Home Edition, I do not
have the installation disk available, the OS was installed
by a company that repaired the laptop after a burn out.

If I were to upgrade to XP professional, would it delete
my files? I'm afraid I cannot afford to lose any of them
for school reasons.

Many thanks to anyone who can helped this frazzled and
panicing student.

Taskbar freezing, CPU use at 100%.. please help