No you are not alone... In order to update the firmware to 7.118, I backed up my 6300 using PC Suite and now I cannot anymore restore all of its contents.
The restoration sequencially restores SMS, contacts, and phone settings. In my case the process stops with an error in the middle of my contacts, without resuming execution for the next contact or the phone settings. The failing contact is always the same. This contact has the particularity to have 2 address lines, so it might be that this special case is not supported by the restoration program... this is just speculation from my side, it can be anything else of course.
Anyway the consequence is that I have now half of my contacts and all of the phone settings left behind in the nbu file.
Appreciated the solution mentioned to use Outlook, but this won't save my settings, nor will save specificities of my contacts that are not compatible with Outlook.
Personally I am not sure this is related to this particular phone model (6300), but must be an issue of PC Suite itself (either the backup or the restore program).
Generally speaking backup and restoration should be the most robust (same level of reliability as the OS itself), otherwise we cannot count on them to execute other programs. Thus they must be simple, like copying files and must mainly rely on the OS. In this funny case, running the phone updater has been safer than the safety measures taken!
I've just had a nightmare restoring contacts to my Nokia which gave varying results (mostly PC suite couldn't read the contacts and not all numbers were restored to my phone) but illogically it fixed itself after I used the phone to copy my contacts from the SIM memory to the phone memory. After that I was able to restore (which writes over all contacts - which was fine) and it worked ok then i.e. all contacts were successfully restored and PC suite synchronises all contacts succefully each time. May be worth a go if you're tried the logical stuff!