I just installed and run (Ubuntu 14.04 x64) the latest SNAP beta 5 and got the following warnings:
Warning - could not install some modules:
jLinda Core Libs - The module Ceres JAI Library was requested in version >= 220.127.116.11 but only 2.0.0 was found.
jLinda Core Libs - The module SNAP Graph Processing Framework (GPF) was requested in version >= 18.104.22.168 but only 2.0.0 was found.
jLinda Core Libs - The module Ceres Runtime Library was requested in version >= 22.214.171.124 but only 2.0.0 was found.
The same warning repeats for many different modules.
Also got the same warning message on Windows 7.
I think you have installed Beta6. On the web page was still the old version number mentioned. I just corrected this.
Or did you really installed Beta5? If so, uninstall it and install Beta6, please.
Maybe things got a bit messed up as we activated module updates for this Beta6 released. If you still have problems please try opening the plugin update dialog from the menu (Tools–>Plugins).
If you get all updates which are available everything should work again.