Update 5 --> Data files have not been converted ? Help!

I just installed Update 5 and now we're getting this error message "Data files have not been converted for this company. To convert datafiles, go to Company Maintenance and click Convert. Do you want to run Company Maintenance now?" (Yes / No)

I don't think we've ever seen this message with other updates.

It worries me to do this because it states that if we do convert at this point that "Data entry files may be cleared. Back up your data before converting."

Is this normal for this update? or are we just messed up somehow?