I am new to Roundcube, so I am probably not providing all of the details needed to answer this question. The problem I am experiencing is with the disk usage indicator in the bottom left hand corner of the Roundcube page. What happens is the disk usage is displayed correctly, then a few hours later it shows 0% and unknown. If I log into Cpanel with my webhosting and change the disk space allotment (for example, from 1 GB to 1.1 GB) the disk usage will work again in Roundcube. A few hours later it stops working, but if I go back into Cpanel and adjust the allotted space, the usage is correct in Roundcube. I've spent some time searching this forum for "disk usage" and I found nothing similar to this problem. I suspect the problem is with my webhost's mail server and not Roundcube, but I don't know what to look for. Any suggestion will be greatly appreciated. Thank you.
The problem is most likely cPanel, it has cron jobs setup to check quotas and is most likely causing the reset. If you have access to RoundCube you can enable imap_debug in the main.inc.php and check the log to verify that the problem is with the mail server.