eclipse project showing a red check mark

Hi,

I recently imported a project in eclipse and one by one added all the dependent jars etc. Now in the project none of the .java files are showing any errors. But the project at the head node still shows a red check mark. I also refreshed and exited eclipse and came back again.

Now I have no idea now where to look for this. Any pointers ? Any log files etc where I can find any further issues
eclipse-error.png