This is rather a Weird problem I encountered when deploying Office Web App for SharePoint 2013. (Not sure about SP2010).
After following MSDN technet of deploying/configuring OWA for SharePoint, Ran a Full Crawl and trying to preview Office Document.
One funny thing that happen to me was that I can preview Excel Document but not Word and PowerPoint document!
never ending load
Toggling Developer Tool to check the package and found
ResReader.ashx giving Status 404 error
The sample request is like below
https://[office web app url]/wv/ResReader.ashx?n=p1.img
The reason being is that i’ve selected F drive for the OWA Installation path (which is not C by default).
Due to some best practices, I always prevent from using C as the installation path. BUT SOMEHOW for Some reason, Office Web Apps needs to be installed in C DRIVE
It may or may not happen as the other environment that i setup was on F drive and it worked Fine. It took me 2 days to dig and the last resolution was to reinstall the OWA.
After installing to C drive. The OWA works as per normal