Often, when opening Windows Explorer, I encounter the following error and Windows Explorer needs to restart:
Here I am using Windows 7 with an Intel Core 2 Duo processor and 2GB of RAM, is this caused by a virus or other causes?
It can be caused by many things. This happens to me a lot when recovering from being taken over by RDP. It doesn't necessarily mean you have a virus but It's likely 3rd party code causing the crash. (Something registered in your shell).
Fortunately explorer's become fairly resillient in windows vista/7 to crashes.
What I suggest is you use this tool to selectively disable shell extensions you don't need and see if the problem goes away.
If you're up to it you can to a systematic approach to pinpoint if any extension is causing this. Should you have no luck here you could have a number of problems but with out more information it's going to be difficult to diagnose.