error message idlemon.dll

hi there When I am on the internet and go to chek my mail
I get a red dot with a x and it says This application has
failed to start because IDLEMON.DLL was not found re-
installing the application may fix the problem-and at the
top it say msmsgs.exe-unable to locate. I then click ok
and my outlook express starts should i be worried or
leave it alone i am running windows xp and outlook exress
6 thanks