Input Field Changing Size On Focus

Hi, I have a problem where by when you click into a field the size of that field increases. This only happens if the width of the field is set by col, it doesn't happen if its a fixed px width and it only happens in IE, not Chrome. See the attached image as an example.

Any ideas as to why this is happening would be appreciated.

Platform Version 9.1.501.0 using the Liverpool theme.

Hi Stuart,

Can you check in IE the applied styles to the input before and after, and see whats different?