this error is coming up every single time.
Every single time you're doing what ? Please be more specific and give the steps/precision about what you are doing before getting this error.
Please help or should I go back to the r59 build?
Ashley will look into this at the end of the week.
Going back to R59 is not advised as it has some known big isssues with file saving.
For now, be patient, make sure it is not just an error getting displayed, whereas the project is still usable, and fill the missing informations as asked in "How to report a bug".
Also, for references, other topics relating apparently the same check failure.
chrisbrobs: sounds like this bug you reported.
No answers for now, (except the tricks already given by Ashley). He will look into it when getting back.
R59 saved projects may cause issues in R60 if they had the "saving" bug you talked about (missing frames). Your current error (combo properties) is (apparently) different.