I have the same problem.
Every day one of subscription deactivates with mentioned notification. I cannot find any options to deal with that.
This subscription has several domains on it and one of them was just resumed from 'hold' status at my registrant. (everyday notifications started after that).
It is very confusing, because this subscription has all unlimited options with no price and no expiration date. Here is a piece of log:
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127.0.0.1 admin [2012-08-06 06:46:42] 'Change status of additional domain' ('Domain Name': 'xxx' => 'xxx', 'Status': '0' => '2')
127.0.0.1 admin [2012-08-06 06:46:42] 'Update additional domain DNS zone status' ('Domain Name': 'xxx' => 'xxx')
127.0.0.1 admin [2012-08-06 06:46:43] 'Update Domain Status' ('Domain Name': 'xxx' => 'xxx', 'Status': '0' => '2')
127.0.0.1 admin [2012-08-06 06:46:43] 'Update Domain Status' ('Domain Name': 'xxx' => 'xxx', 'Status': '0' => '2')
127.0.0.1 admin [2012-08-06 06:46:43] 'Update Domain DNS Zone' ('Domain Name': 'xxx' => 'xxx')
127.0.0.1 admin [2012-08-06 06:46:43] 'Change status of additional domain' ('Domain Name': 'xxx' => 'xxx', 'Status': '0' => '2')
127.0.0.1 admin [2012-08-06 06:46:43] 'Update additional domain DNS zone status' ('Domain Name': 'xxx' => 'xxx')
127.0.0.1 admin [2012-08-06 06:46:43] 'Change status of additional domain' ('Domain Name': 'xxx' => 'xxx', 'Status': '0' => '2')
127.0.0.1 admin [2012-08-06 06:46:43] 'Update additional domain DNS zone status' ('Domain Name': 'xxx' => 'xxx')
127.0.0.1 admin [2012-08-06 06:46:43] 'Change status of additional domain' ('Domain Name': 'xxx' => 'xxx', 'Status': '0' => '2')
127.0.0.1 admin [2012-08-06 06:46:43] 'Update additional domain DNS zone status' ('Domain Name': 'xxx' => 'xxx')
127.0.0.1 admin [2012-08-06 06:46:43] 'Change status of additional domain' ('Domain Name': 'xxx' => 'xxx', 'Status': '0' => '2')
127.0.0.1 admin [2012-08-06 06:46:43] 'Update additional domain DNS zone status' ('Domain Name': 'xxx' => 'xxx')
127.0.0.1 admin [2012-08-06 06:46:44] 'Update Domain Status' ('Domain Name': 'xxx' => 'xxx', 'Status': '0' => '2')
127.0.0.1 admin [2012-08-06 06:46:44] 'Update Domain Status' ('Domain Name': 'xxx' => 'xxx', 'Status': '0' => '256')
127.0.0.1 [2012-08-06 06:47:02] 'Update additional domain DNS zone status' ('Domain Name': 'xxx' => 'xxx')
127.0.0.1 [2012-08-06 06:47:03] 'Update Domain DNS Zone' ('Domain Name': 'xxx' => 'xxx')
127.0.0.1 [2012-08-06 06:47:03] 'Update additional domain DNS zone status' ('Domain Name': 'xxx' => 'xxx')
127.0.0.1 [2012-08-06 06:47:03] 'Update additional domain DNS zone status' ('Domain Name': 'xxx' => 'xxx')
127.0.0.1 [2012-08-06 06:47:03] 'Update additional domain DNS zone status' ('Domain Name': 'xxx' => 'xxx')
127.0.0.1 [2012-08-06 06:47:03] 'Update additional domain DNS zone status' ('Domain Name': 'xxx' => 'xxx')