[imp] Unable to log-in; stuck on "Mail Maintenance Operations - Confirmation"

[Robert Smithson]

Hi,
 
I've had a Horde/IMP installation up and running for the past month.
Today, trying to login, I got:
 

Mail Maintenance Operations - Confirmation 

 

Notice - Mail is ready to perform the maintenance operations checked
below. 
Check the box for any operation(s) you want to perform at this time. 
 
Etc. 
 
Unfortunately, no matter what I choose, I get kicked back to the log-in
screen. 
 
Has anyone seen this problem?
 
Thanks,
 
Robert