Need help (regarding Internet Explorer)

Hey,
I had some problems with internet Explorer because of which so tools such as XGen SEO and Twitter Attacks are having problem in running!
When I login into my twitter account (or even paypal account) it shows "Certificate Error"! When I click on: " Continue to this website (not recommended)" it successfully goes to the next page! But obviously Hindershttps://twitter.com/sessions the automation process!
This is the Screen Shot:

Please advice

Goto Tools/Internet Options/Advanced and click on reset to reset IE to default.
Also check date / time on PC is correct - that can cause this issue too.
HTH