Installed from the same source all 5 times ? Might be a corrupted source. Bad iso ... the whole check the md5 checksum and burn the iso at slower speeds spiel, blahblahblah. Or are you watching what's being installed from the repos ? You might be allowing something you don't want to be dl'ed and installed 5 times running. That's crapping out your system.
If you're getting stuff that's sid, or testing quality. Software in a testing repo, is said to sometimes have issues and bugs that haven't been worked out yet. ( edit ) 1st time I finished installing Mint, the update manager told me I had 200+ shiny new packages waiting for me to dl and install.
Thought an updated OS sounds great ! So I selected all, dl'ed everything and installed the whole shebang. A bunch of those were packages rated 3 and 4 ( < not safe ). It screwed the OS up and I thought Mint suks !
Didn't want to quit, so did a fresh install. Was more cautious about what update packages were installed. Now have the update manager set to only show packages rated 1's and 2's. Mint's running like a charm now.
random note: System restore is next to worthless for recovering from anything really serious in my experience, shrugs. They've made tons of ways to backup and restore your new Linux OS ... You've just got to learn about them and use them, shrugs again.