In this case I think the best solution is, uninstall the SNAP, be sure to delete all the folders related to SNAP after uninstall it for instance, .SNAP .gdal, etcl.
Then redownload and install the latest version, concerning the RAM, I think 4, and 8 GB RAM are not enough, but 16 GB could work fine,
To increasing the memory, please take a look at the following post,