Aastra 53i keeps asking for"Enter Extension"

Hi,

I am running a small setup at a customer site with TB2.6.2.2, 2 x 51i and 2 x 53i Aastra phones. I am also running the new XML 2.2.1 script. All the phones are powered by a small 8 port PoE unmanaged switch with PCs daisy chained off the phones.

I have been having nothing but problems with this setup including phones rebooting, phones showing Busy while no one is on the phone and this morning the receptionist's phone (the most critical one) seem to have been rebooted over night and now asking for an extension number as if it can't find its own existing profile on the server. Once I entered the extension number and password it came right.

The phones are all running the lateset firmware which comes with the XML script.

I know that there could be many possibilities, but this setup is so basic that even voicemail to email is not being used except for the receptioist. TB is configured with singe Ring Grouop that receives all incoming calls via a single DDI. A sinlg SIP trunk carries all inbound/outbound calls and no PSTN.

Could that be a Network issue, but why other phones were fine.
Could that be a XML script issue????
Could it be this 2.5.x.x fimware issue, other posts talk about better stick to 2.2.1.25 much more stable???

Any feedback, support similar experiences are appreciated.

Thanks