[imp] IMAP errors on Android Browser

[Chris]

Hi.

I have imp configured and working nicely now, that is it works nicely  
with everything except when I'm using the "Mobile" interface.

I have tried it on my android with two different browsers and on the  
desktop (still using the "Mobile" interface), and the results are the  
same.

I login, click (or push) on "Mail", I see I have  unread messages on  
the "Inbox" bar.  I push/click on "Inbox", then I get this error:

"IMAP error: Mailbox does not exist, or must be subscribed to."

Which, of course, is nonsense, because it can see I have unread  
messages (and it works fine with the other interfaces).

I have this coming up in my syslog:

[imp] PHP ERROR: Trying to get property of non-object [pid 12284 on  
line 353 of "/var/www/horde/imp/lib/Imap.php"]
[imp] IMAP error: Mailbox does not exist, or must be subscribed to.  
[pid 12284 on line 340 of "/var/www/horde/imp/lib/Imap.php"]
[imp] PHP ERROR: json_encode(): Invalid UTF-8 sequence in argument  
[pid 12284 on line 242 of "/usr/share/php/Horde/Serialize.php"]
[imp] PHP ERROR: json_encode(): Invalid UTF-8 sequence in argument  
[pid 12284 on line 289 of "/usr/share/php/Horde/Prefs/Scope.php"]
I have googled this, but come up with nothing.

Any ideas on how to fix this?

Thank you very much.

-Chris