Drop down menu hidden on random systems

Hi All,

I have recently had my website re done by a web designer using word press which is fantastic. I am really pleased with the site. As the website was handed over to me recently i have been updating the info adding my content and learning how to make changes in my dashboard etc. All of a sudden out of the blue, the drop down menu on my site began to hide behind the tv screen layer and slogan layer of my website. The weird thing is that this has happened on my home pc which is using xp internet explorer 8 but it is fine in other browsers such as Google chrome. The other weird anomaly is that on my laptop which is using xp internet explorer 8 there is no problem.

I had my colleague check his systems which is using xp ie7 and he is also noticing the problem of the drop down menu but again when i checked other computers with xp and vista using ie8 there seems to be no problem.

My web designer is also confused as to why this is happening as he can see no problems his end, but this is a problem as varying clients use different versions of browsers and i need it to be compatible with all browsers, if it is the browser which is causing the problem?

Any feedback or help will be greatly appreciated; by the way the website is http://www.RKDFilms.com

Thank You