Can't open control panel items and "run dll as an app" err..

[alex1972]

Tech newbie looking for some basic guidance. Am running Windows XP on a Dell
Inspiron E1705.

Noticed a problem when I tried to adjust the date and time to our new
timezone: get a "run dll as an app" error message. Then noticed I can't open
the display, system, or several other icons in the control panel. No error
messages there, they just don't open. Same when I click on "properties" for
just about anything.

Have run Norton Antivirus, Spybot, and the Windows Live virus scans and they
found nothing. Can't run the Windows Malware Tool because I get an error
message with it too. Also tried doing a System Restore to a couple months
ago, but still have the errors.

Where do I even begin to troubleshoot? Seems like a lot going wrong.