Country overlay covering part / entire content?

Is this a problem for SEO?

[financialhost]

I have recently decided to use an overlay that users can choose to pick the country of their choice. The overlay was originally going to be a little bigger than the average pop up & cover part of our content.

It would only appear the first time the user appeared on the site.

The designer i am working with is proposing to use an overla y to cover the entire content - forcing users to pick a country. The size would be 900x1200px

I worry that this could have an effect on SEO & may be considered a cloaking technique.

Can anyone comment on this?
Is it risky to cover the entire screen with the overlay?
Does size make a difference?

[Kufu]

That wouldn't really be cloaking, but I would stay away from anything that might be remotely suspect.

The best rule of thumb to go by is that if what the search engines see and what your visitors see is significantly (I'd personally say 'at all different') different, then you may be asking for trouble.