I would guess there was a script running a "replace" script step. Check your code for where that may be, If it acted on more records than intended that would be a problem...
Updating is also llikely if there is any looping script, especially if it edits values which trigger any other auto-enter/evaluate changes to other fields.
We found that WAN connections were so slow for some of the Loop or Replace processes that we tested for the user's connection address and kept WAN connections from running such processes so they wouldn't be tied up for 20–30 minutes on a process that took 1/10th as long on LAN.
And of course the distinct possibility that the dialog didn't actually say "Updating" but something completely different.
I know, not helpful...but that is the scenario I'm working on at the moment. A dialog that is not FM related, OS related, or a custom dialog I created. A somewhat "some box popped up, I don't know what it said, I just closed it and rebooted". lol
I.E. - I saw the script was taking a while so I decided to run my system updates while I waited...