Internet explorer was closed DEP error message

When I am trying to get to my Internet web page on my Windows Vista premium machine, I get an error message.
I have IE 7 installed on my machine and when I click on that, I first get that my IE has stopped working. Then it gives me an option to search for online solutions or just click on ok. When I go to search for online solutions, it comes up with the following error message.
Internet Explorer was closed. To help protect your computer, Data Execution Prevention has closed Internet Explorer. Click to learn more.
It was working well before and all of a sudden the error message started coming up with the pop ups.
Please help.
