Blogstyle - images floating into sidebar

[Robotic]

Hello,

I am using a blogstyle layout (as opposed to the default 'magazine' style), however all of the centrally aligned images in my posts are floating over into the sidebar (to the right of the page). This only appears to be happening with images wider that 250 pixels.

However this issue only appears on the homepage (i.e. the normal pages - page 1, page 2, etc etc) - yet in the 'page_blog' and category mode the same images are correctly aligned centrally.

I've searched this forum and the wider Internet but I have been unable to find a solution. The only solution I can think of at the moment is to go back through 900 odd posts and give each image a nonalign - but this would look just as messy as the images would be too far to the left of the posts.

Can anyone offer some better suggestions - this one has me stumped. I'd be happy to PM the link to my site if that would help.

Thanks in advance.