Standard and Basic vews in Gmail

"Recently my google email won't open in standard view, but it will open in basic html. Why is this and what is the difference between these two views?"

 Basic view is a slimmed down version of Gmail, with less features.  It's designed to allow people with old/esoteric web browsers still access Gmail.

Google explain it quite well here:

 

Standard view and basic HTML view

 

To see if your browser is on Google's buddy list,see this article, which lists all browsers which can do Standard View and those which must use Basic View.

 

Supported browsers

 If your browser is on the supported list but will only do Basic view, it would be prudent to make sure it is updated to the latest version and if that doesn't work, reinstall the browser, or try a new one.  

Maybe this is your opportunity to try out the brand new Google Chrome ?