POE failure causing phone to reboot

[jasit]

In the last 6 months, we have about 5 phones have the issue that POE no longer works properly. Seems to have enough power to start the phone, but once it starts to set it's self up, it reboots again. If I plug in the wall power adapter, phone will work, or if I replace the phone with a spare phone the poe network port seems to be working fine.

I have tried the same phone on different switches, and it seems to be an issue with the phone.

Has anyone else come across this, or is there a component that needs to be replaced on the phones processor board? We have been very happy with the phones and they are only about 5 years old. I would hate to have to replace them.

Thanks

Jasit