64-bit Windows Installer Issue

Having recently installed XP x64 on my new computer, I've been playing games on it without a problem up until just lately I needed to look something up in one of the manuals, which I only have a PDF copy of. The OS appearently did not come with a copy of Adobe Reader or similar, so I attempted to install the latest version I had from a CD. It starts, brings up it's splash screen, then tells me that there is an error in the windows installer and closes.

Trying to install LEGO Star Wars brings about a similar error, but it instead tells me that it can't start windows installer. Can anyone help?