IE Browser pb ?

Hi,

When using IE suddenly closed, get back to initial screen without error message.
Then no possibility to use anymore IE as well as "control Panel" and computer navigation ("search", "explore", "my Computer"...).
Tried a restore from day before... didn't work.
Tried updated of windows XP : no effect.
Scan for virus with Norton : nothing detectable.

Then I tried to start my computer in "SAfe Mode"... and in this mode IE works and I can use "control Panel".

Is someone could help me in identified the problem and give me some clues (or more) to fix the problem ?

Thanks,
Kathy