Issues with linksys SPA 2102 and Asterisk 1.4

Last weekend we upgraded to asterisk 1.4.11.
After a while (time varies) the SPA starts showing as not registered. If we turn quality on then we see a not reachable message in the log when it goes away but otherwise nothing else.
I do see the registration string
[Sep 11 13:44:23] VERBOSE[5332] logger.c: – Registered SIP ‘410’ at port 16637 expires 360

If somebody is on a call when this issue happens they first loose the ability to transmit but continue to be able to hear the other person for a bit then the line goes dead and everything acts as you expect with a device that is not registered.

The asterisk server is reachable the whole time so there is no reason it shold be timing out or anything. This effecting 6 SPA ATA’s. We did not see this issue before the upgrade.

Rebooting the SPA brings it right back, but only for a while.

Has anyone else seen this type of issue or can suggest a change on either client or server that might address this issue?

thanks, any advice imprecated.