Unable to Log In to Online Vault After Merging Large Backup File

In migrating data off of a Windows XP machine to a Windows 8.1 machine I ran into this issue.  The newer machine has an online vault with only about 8 entries.  I exported the contents of my local vault on the XP machine, which contained about 60 entries, to a flash drive and then merged that file with the existing online vault.  The merge was successful and all of the entries appeared in the vault.  But after logging out of the vault and then trying to log back in, I got the dreaded "operation has timed out" error and ended up having to recreate the vault.  Again I first imported the 8 entries from a backup and then tried to merge the file containing the other 60 entries.  Same result - had to again recreate the vault.  For my third attempt I first imported the larger file and then merged the remaining 8-entry file.  Success!  So, apparently, even though merging the larger file succeeded in my earlier attempts, it apparently corrupts the vault, making future access impossible, whereas this does not happen when merging a smaller file. 

 

This appears to be the same issue discussed in an earlier thread, although I was able to work around the issue without reinstalling Norton:

 

http://community.norton.com/t5/Norton-Toolbar-Norton-Identity/Vault-unavailable-after-merging-local-with-online/m-p/926485/highlight/true#M9500