This is a wild guess (as I've had similar problems with Fixed Asset Manager in the past).....are you using the program on your "third" monitor?  If so, try using it on your first or second monitor and the drop-down menus will work.

Can't make that one up!

All of this is likely your browser having an issue.  Clear your cache. You may need to a search for the browser you are using,  as each flavor has it's own corrections. Here is how to do it in Chrome. https://support.google.com/accounts/answer/32050?