Phone Sim 'disconnects' randomly

[#1]

Was loving my X10 Mini Pro.

But now it has recently started 'disconnecting'.  I pick it up wondering why no phone calls nor texts are coming through and it's because I need to put my SIM unlock code in.  Once I do that the phone is fine - but only for a short while.  I check and there it is again, "enter PIN code".

I've had about three weeks use out of it, and now this.

Is it an app [have started uninstalling one by one]

Is it the software repair I did [when I thought I was updating software to new OS]

Does it have to go back?

If anyone has any idea, please... I would be very grateful to hear it.

[Er_Kannan · Accepted solution]

Have you got any task killer applications installed on your phone? Killing of the latest backup software causes an issue like the one you mentioned. Add backup program to ignore list of your task killer application.

[#3]

!!!!

Well I was about to chuck in the towel beause of this but you, Er.Kannan, have saved my lovely phone.

Thank you for coming up with that.  I would never have found the solution on my own.

Baffled by such a scary moment.

Thank you thank you thank you.

[I was using Advanced Task Killer > I added the new Backup and Restore app to the Ignore List > so far no shut downs]