Desktop settings change.

When I boot up, my desktop settings have changed. This only happens when I
have used Internet explorer the previous time.

Desktop Properties - appearance - windows and buttons, there are usually two
options..Windows XP style and windows classic style.only Windows classic
style is available. It does not give me the option to change.

If I use desktop.properties .themes, and apply windows XP, it does not
change. I sometimes have to reboot four or five times before it gives me the
option of XP style in Desktop Properties - appearance - windows and buttons.

I am using XP Professional  .. build 2600

Any help will be greatly appreciated.

Jules