Sony Ericsson Xperia X10 — hey

hey i m not able to upgrade my xperia x10 from 1.6 to2.1 when i m upgrade it from PC COMPANION thn every tym an error occur that phone software update is aborted.
click retry to restart the phone software update but when i m restart the phone n retrying then the same error occured
wat should i do please help me

Is it the official Xperia update you are trying to install. I would contact sony support and ask them what to do, or try taking it to the place you bought it for help.

Unfortunately it's often up to your service provider to offer you an update, even if the manufacturer released it long ago.
Therefore some Xperia phones still run on 1.6.
Your only option may be to root your phone, install e.g. the 'Generic Nordic' firmware and then get 2.1 or with time even 2.3.
XDA forums have some good guides on how to do such a thing.
Good luck.