unlocked galaxy tab firmware upgrade questions

[nusung]

HI,

I have a samsung galaxy tab that I purchased unlocked and believe originally came from the UK. I have Kies 2.0 installed on an xp and get an error when upgrading the firmware. It is a generic message saying "firmware failed to upgrade. Unknown Error".

1. Are there any issues with upgrading firmware on an unlocked Tab?

2. Will the upgrade override the unlocked tab?

3. Any clues on why the firmware does not upgrade?

thank you.