A solution for "No service" problem in HTC Android Phones (Hero, Legend, Desire)

Since last few months I have been using a HTC Legend phone. There was no problems with the phone and then suddenly I started having the "No network" error. The phone was dropping down the network minimum 4 times a day and it was not possible to re-register to the network. The only solution was to restart the phone or turn on and off the airplane mode. The above did happen also if when the phone was on my desk untouched so I thought the 2G/3G switching that is mentioned by many people could not really be the reason.

I have send it twice to repair without any change. Luckily it is quite easy to restore the android phone, contacts are synchronised  with your gmail and the list of all installed apps can be found in the market so it was easy to install them back.

Funny think is that Meteor Ireland and HTC are not able to work out what causes this annoying problem. As I have seen on the Meteor Talk to Us,  Meteor claims that the majority of users are perfectly happy with their HTC Android devices. Should we ask - do they just not bother to complain or they really don't have the issue.

Because I really like the Legend, I started to think why it worked before and doesn't work now. The only difference were the installed apps.
I thought the culprit may be the Advanced Task Killer, so I uninstalled it, unfortunately the problem was still there.
I observed in the past, that I had the error after installing the Nimbuzz app, then I uninstalled it and it was gone. This time there was a Rebtel app on my phone. Both application probably monitor the network connection and probably hook to the network connection process, I didn't check it but I would think they work like this. The argument for the above was also the fact that I couldn't re-register to the network without restarting the phone. I thought it was because the network connection process is gone.
My theory is that the problem is caused by a number of applications that hook to the network connection process and cause its crash.

I have uninstalled both apps and since few days I am again a happy HTC Legend user.
Of course the above is just a theory that needs to be proved, but it solved my problem so I thought I publish it so it may help to solve the problem once and for all. At the same time I am not determined to dig deeper into the technical details.  I would thing that Meteor or HTC IT guys should take it from there.

Update:
Today - 06/10/2010 - after few weeks of using the phone I installed skype and the "no service" appeared again. This is a shame I can't use skype on my phone.

09/12/2010 - after installing Froyo, issue does not exist any more.
It is just worth mentioning that after the system update it is required to select Access Point otherwise there is no mobile internet.