Eclipse – Your project contains error(s), please fix them before running your application.

Today I got trapped in a really weird situation. while compiling an android app in eclipse,I got alerts Your project contains error(s), please fix them before running your application.
ACTUALLY there was no error in code; I tried project -> clean. TOUGH LUCK :(
I was pretty annoyed, because I was not able to run my app to test on my Android device.
After doing a lot of investigation:

I got that this is a little annoyance you’re going to get now and then. To fix it, just use the “Problems” window which is docked at the bottom by default, right click on the Error(s) listed and delete.

Try to run now. Yay! Its running now...

If still any issue, might be you need to run project - clean.

Hope this helps!