One way to test is to Safe Boot from the HD, (holding Shift key down at bootup), run Disk Utility in Applications>Utilities, then highlight your drive, click on Repair Permissions, Test for problem in Safe Mode...
PS. Safe boot may stay on the gray radian for a long time, let it go, it's trying to repair the Hard Drive
Reboot, test again.
If it only does it in Regular Boot, then it could be some hardware problem like Video card, (Quartz is turned off in Safe Mode), or Airport, or 3rd party add-on, Check System Preferences>Accounts>Login Items window to see if it or something relevant is listed.
Check the System Preferences>Other Row, for 3rd party Pref Panes.
Also look in these if they exist, some are invisible...
Open Console in Applications>Utilities, check the system log for the date/time of the last problem & next startup for clues.
Sorry for the delay, but I wanted to check things over a longer period.
As usual, the safe mode verify/fix permissions took a long time, had a long list, and had no discernible effect on my computer. Word behaved for a while, but then today the spinning wheel came up when I tried to enter text in an existing 52 KB document. It crashed twice, and then began to work once I restarted the computer for the third time. I tried the safe mode again, and Word functioned decently that way also.
It just appears that Word occasionally screws up, and sometimes on new and sometimes on existing "Compatibility Mode" documents. Switching from safe to regular mode does not seem to affect Word. I have not seen those other names, but will continue to look. System Preferences>Other Row does not seem to exist on my iMac.
I just think that Microsoft makes terrible software; their updates take hours to download, and Word is very unstable.