May I know since when you are facing this issue? The symptomps you have described tells that it might be an issue with the operating system of the pc. looks like you are using windows xp in your pc. You can try running a system restore. Start>All Programs>Accesories>System tools>System Restore. Then you will get the window of system restore and you will have click on the option that says Restore My Computer to an earlier date/earlier point in time. Once u click on that it will show u the calender. If u are sure about the point in time from which u r facing this issue look for the date. But you will be able to restore ur pc only to those dates that are marked in bold. Click on that date and keep hitting next until it starts the restoration. If it does not help then try this. Click on start>Control panel>Add or remove programs. once the add or remove programs window comes up on the left hand column u will get an option called Add/Remove Windows Components.
On the list that comes up u will get the options for Internet Explorer and Outlook Express. Uncheck them and restart the pc. And follow the same process to put check marks on those two options. IF this does not help most likely u will have reformat the hard drive and reinstall windows. If u dont want to run the format then u can use another browser like mozilla firefox and use another email client like Windows live mail and u can download them free from web. http://www.mozilla.com/en-US/firefox/
is the link to download mozilla firefox and http://explore.live.com/windows-live-mail?os=other
is the link to download the latest version of live mail.