Opened Older CPR File Now Latest CPR Crashing Cubase

So I’ve been saving off CPR files as backups with dates. For example Song.cpr is the file I always work with and then I’ll save off Song20180711.cpr, Song20180710.cpr, Song20180709.cpr, etc. So today I wanted to check a VST instrument level in an older version… so I opened up the older version, opened up the VST to look at the level, and the project became frozen, so I killed Cubase in Task Manager which had a Status of Not Responding. Then opened my latest version Song.cpr and now all the VST instruments are acting up. They take forever to open and often put Cubase into a Not Responding state.

Anyone have any idea what’s going on here? Thanks in advance for your help!

Cubase 5 64
Windows 7 64


Or can anyone just tell me whether or not this is something that should or should not be happening?