Power Out of Range ?

Hi
Support ticket: 20285118

ReadyNas Ultra II

I've been away for a few months. Since I returned I've been getting this is Status>Health:

Sun Jan 6 09:30:45 WET 2013 V+12 power is out of normal range [expected: 12.00 current: 10.82]. Sun Jan 6 09:25:29 WET 2013 V+12 power is out of normal range [expected: 12.00 current: 10.72]. Sun Jan 6 09:20:12 WET 2013 V+12 power is out of normal range [expected: 12.00 current: 10.88]. Sun Jan 6 09:13:26 WET 2013 V+12 power is out of normal range [expected: 12.00 current: 10.77]. Sun Jan 6 09:13:16 WET 2013 Fan will be recalibrated over the next few minutes. Sun Jan 6 09:08:10 WET 2013 V+12 power is out of normal range [expected: 12.00 current: 10.93]. Sun Jan 6 09:02:53 WET 2013 V+12 power is out of normal range [expected: 12.00 current: 10.88]. Sun Jan 6 08:57:37 WET 2013 V+12 power is out of normal range [expected: 12.00 current: 10.98]. Sun Jan 6 08:52:20 WET 2013 V+12 power is out of normal range [expected: 12.00 current: 10.77]. Sun Jan 6 08:47:04 WET 2013 V+12 power is out of normal range [expected: 12.00 current: 10.67]. Sun Jan 6 08:41:47 WET 2013 V+12 power is out of normal range [expected: 12.00 current: 10.56]. Sun Jan 6 08:36:31 WET 2013 V+12 power is out of normal range [expected: 12.00 current: 10.61]. Sun Jan 6 08:31:14 WET 2013 V+12 power is out of normal range [expected: 12.00 current: 10.56]. Sun Jan 6 08:31:13 WET 2013 System is up. Sat Jan 5 16:32:16 WET 2013 V+12 power is out of normal range [expected: 12.00 current: 11.14]. Sat Jan 5 16:26:12 WET 2013 V+12 power is out of normal range [expected: 12.00 current: 11.08]. Sat Jan 5 16:17:11 WET 2013 V+12 power is out of normal range [expected: 12.00 current: 11.14]. Sat Jan 5 16:11:54 WET 2013 V+12 power is out of normal range [expected: 12.00 current: 11.14]. Sat Jan 5 16:05:34 WET 2013 V+12 power is out of normal range [expected: 12.00 current: 11.03]. Sat Jan 5 16:03:42 WET 2013 V+12 power is out of normal range [expected: 12.00 current: 11.14]. Sat Jan 5 15:58:25 WET 2013 V+12 power is out of normal range [expected: 12.00 current: 11.08]. Sat Jan 5 15:50:13 WET 2013 V+12 power is out of normal range [expected: 12.00 current: 11.14]. Sat Jan 5 15:45:16 WET 2013 Backup finished. [Job 001] .... Sat Jan 5 15:22:15 WET 2013 V+12 power is out of normal range [expected: 12.00 current: 11.08]. Sat Jan 5 15:21:58 WET 2013 V+12 power is out of normal range [expected: 12.00 current: 11.08]. Sat Jan 5 15:21:41 WET 2013 V+12 power is out of normal range [expected: 12.00 current: 11.14]. Sat Jan 5 15:21:24 WET 2013 V+12 power is out of normal range [expected: 12.00 current: 11.03]. Sat Jan 5 15:21:07 WET 2013 V+12 power is out of normal range [expected: 12.00 current: 11.08]. Sat Jan 5 15:20:50 WET 2013 V+12 power is out of normal range [expected: 12.00 current: 11.03]. Sat Jan 5 15:20:33 WET 2013 V+12 power is out of normal range [expected: 12.00 current: 11.14]. Sat Jan 5 15:20:16 WET 2013 V+12 power is out of normal range [expected: 12.00 current: 11.03]. Sat Jan 5 15:19:59 WET 2013 V+12 power is out of normal range [expected: 12.00 current: 10.88]. Sat Jan 5 15:19:42 WET 2013 V+12 power is out of normal range [expected: 12.00 current: 10.93]. Sat Jan 5 15:19:26 WET 2013 V+12 power is out of normal range [expected: 12.00 current: 10.93]. Sat Jan 5 15:19:06 WET 2013 Backup finished. [Job 006] Sat Jan 5 15:18:53 WET 2013 V+12 power is out of normal range [expected: 12.00 current: 10.93]. Sat Jan 5 15:18:35 WET 2013 V+12 power is out of normal range [expected: 12.00 current: 11.03]. Sat Jan 5 15:18:18 WET 2013 V+12 power is out of normal range [expected: 12.00 current: 11.08]. Sat Jan 5 15:18:01 WET 2013 V+12 power is out of normal range [expected: 12.00 current: 11.08]. Sat Jan 5 15:17:44 WET 2013 V+12 power is out of normal range [expected: 12.00 current: 11.08]. ....

What does it mean and what should I do, please?
I bought it 4 May 2011

Many thanks,
David