Registry/Application/Browser problems

Archived from groups: microsoft.public.windowsxp.help_and_support (More info?)

I have messed with the permissions to successfully install itunes/quicktime
without receiving all those errors, but I may have messed something up. There
are 4 accounts on this pc, all are listed as pc admins. Whenever one of the
accounts are not setup to be an admin an error box appears about every 20-30
seconds, sometimes when this box appears it'll close any browser windows or
apps. When they're set to admins the error box never shows up. Sometimes when
I start an application or open a browser window I will not be able to click
on anything. It'll show me clicking the seleced tabs, but it won't proceed to
do what I asked. For instance when I open realplayer I cannot move the
window, it stays in the top left corner of the screen. Sometimes when my mom
plays Pogo and she goes to click on ANYTHING it won't work. This happens
randomly and we either have to close the window and try again or log off then
on. These problems only started to occur after I messed with the registry in
hkey local machine; software; classes; cdda. If anyone knows how to fix my
problem or set the cdda section back to default all help would be appreciated.