I've seen that.
With close observation, I noticed that on my machine, the number of windows seemed to be a factor--the more windows and browser tabs I had open, the sooner all windows and tabs failed to open, draw and/or update correctly.
In my case, uninstalling and re-installing FileMaker 10 fixed the problem.
I have uninstalled and re-installed FM 10 and I still have the same problem. It's to the point now that the user has to close all running programs for FM Pro 10 to launch without an error.
I make my user local admin. Uninstalled FM 10 again. Reinstalled with users credentials (as local admin). Removed user from local admin and rebooted the system and it appears that it is working as designed.