You can open an SR for this and provide logs of the VC and the web client.
Also make sure that the dns name of the VCVA is resolvable from your machine, otherwise it most probably ends with the error you hit.
By the way, did you have experience with previous version of the VMware vSphere Web Client on the same machine/browser? If yes, could you try clearing your browser's cache, because it could be too aggressive on caching flash movies.
Meantime, if it is doable, can you try a fresh installation of the VC appliance of 5300 build and try again with OVF deployment?