Word WebApp encountered an unexpected error /Excel WebApp unable to process the request

In one of my newly created web application, the users tried to open Excel/Word documents using browsers. They were getting the following error and I had to investigate.

 I checked all the services on the WFE and Word viewer service, Excel calculation service were running. When i checked the event viewer for errors, I found the following in event viewer, which ringed the bell

Then I checked the Central Admin->Application Management-> Select the web application -> Service connections -> Configure service application associations and found that Excel Service and Word viewing service is not configured for this web application. When I enabled those for this application, users were able to view Excel/Word using browser. Hope this helps for you!!!

Microsoft SharePoint Word Web App - Unable to open word files in client

When I tried opening word documents from a SharePoint library it was opening in in WebApps. When ti tried to open in word it was throwing a following error.

I thought something is wrong in my workstation. Then I found that I was using 64bit IE and switched to 32 bit IE. I am now able to open word documents using 32 bit IE. Wondering what could be the reason? Can any one help me?