Can't access or enter cells in sheet

Can't access or enter cells in sheet

Hi

Someone has shared a sheet to me not sure where the problem lies but before i signed up i could view the sheet scroll up and down enter cells even thought i could not edit.

Now once i'm signed up i can't do either. I have tried on an xp, vista and a mac, using Firefox 3 and Internet exploerer 7.0 as well as safari and i get no luck.

On some browsers i get loading xyz [sheet name] but it never disappears.

Do i need to modify a setting on my browser, is shared sheet corrupted.

Please can someone Help

Thanks

Nadeem