Active Theme Not Updating (WP v3.3.1)

I am having problems with my installation of WordPress v3.3.1 into the root of my domain at redflagprojects.com. I’m at a loss for why this is happening as I’ve reinstalled WordPress (via my host) over 3 times but still the fact remains that if you try to change the active theme, you’ll receive a message stating that ‘the theme has been changed’ yet it still shows the previously installed theme as ‘active’.

This is preventing me from setting up my ‘new’ theme. I suspected that perhaps the problem was with the theme itself but it does not appear to be the case because I’ve uploaded multiple themes now from different authors (themes that I’ve successfully installed elsewhere) and the same thing happens. Even if you select one of the older pre-installed WordPress themes (like the 2010 theme), it still will show that the WP 2012 theme is active.

Is there anyone experiencing the same problems with this WP version? Is anyone able to help?

I appreciate any assistance!

Thanks in advance,
Denise.