Transfer of files, backup, archiving-please refer to Andrew Hewe

for Andrew Hewertson please.
hello Andrew. We spoke this morning about trouble shooting with file transfers and backups of ordinary files and pst files. I am receiving error messages when I backup files from my laptop to an external hard drive or to my new laptop fom the old laptop.
The messages say things such as;
1. file name too long for destination folder.
2. folder/file cannot be moved.
3. pst file cannot be moved.
4. insufficeient space availalble-even though there is more than enough.

I have purchased a new laptop and I am tying to transfer everything across to the new laptiop. also I do a backup of everything every 3 weeks and encounter the above problems. so a lot of files are not backed up.