7912 phones display bogus dates in call logs

[e.groves]

I have a customer whose 7912 phones intermittently display 0/0 as the date for received and missed calls in the logs. I have upgraded the phones to the latest load and conferred with Cisco. I've also tried other 7912s and I get the same result. Does anyone know what may be causing this?

[ebreniz]

Could you please check the configuration of the time/date group

http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_administration_guide_chapter09186a00801ecf70.html

[e.groves]

I should have given this information in the original message. The time/date group is configured correctly. The customer has only one and all phones use it, including some 7940s and 7960s. The only phones with the problem are the 7912s. All phones display the correct time. The incorrect date only shows up in the call logs on an intermittent basis and, after further investigation it seems to be only four of the 7912s. We've tried different phones replacing these and the problem still occurs. I'm going to try changing switchports for grins. Voice signaling and quality are good.