TIVO Tuning Adaptor spontaneous restart/reboot

For the past two months, the two Cisco Tuning Adaptors associated with my two TIVO's have been restarting by themselves. For a while they were synchronized i.e. they both rebooted at the same time. Now they both have a mind of their own. Every time a TA restarts, the TIVO gives up on any recordings and interrupts any viewing with messages about the TA. You get a second message once the TA restarts, also with terminated recordings.

Reboot time varies a lot. Sometimes a couple times a day, sometimes 2 or 3 times a week. Often during the 4th quarter of a Suns or Warriors basket ball game. This is getting old.

Cox has been out 4 times. Replaced both tuning adaptors and cable cards. No change. They have blamed it on noise issues, aka ingress (first guy). In house cabling - second guy who replaced every connector he could find. No change. Third guy blamed my amplifier and installed his own. Fourth guy blamed the amplifier installed by the third guy. He replaced it with a mid split amplifier. No change.

Problem remains with no significant change. Very difficult to test since it takes between 12 and 36 hours for a TA to reboot on its own.
Guy number 5 is now scheduled to come out. Perhaps he will have better luck.

My head is spinning. Smells like a head end issue to me. Is it just coincidence that these problems began with the death of the 1000 series channels, increased modem speed and the death of VOD?

And just today, they have suddenly been rebooting in synchronization.  Three times so far.  Both rebooted within seconds of one another....

Any suggestions would be appreciated.