GAP in design when displaying in IE

Hello, I am new to website design, and I am having problems with making a design (which was designed for me awhile ago) the same across browsers as it appears correct in Mozilla, but there is a huge gap in IE. Can anyone tell me if there is an error in the code? I do not see a gap anywhere.
Many thanks!

the url is:

sorry for being brutally honest, but I’d say you should start again. This code of the site looks like it’s been designed in the 90s, with table layout and a lot of other bad pracitces (I’m not going into much detail here, sorry), and the drop down menu (services, gallery) doesn’t work.

My advice would be to get Wordpress or Joomla (personally, I’d prefer Wordpress) and try to convert the layout into a template for either one.