Cannot run exe across network or internet

I cannot run an exe file across my network or the internet on one of my

computers. All run Windows XP and all other computers can. The only

difference is the one in question runs XP media center.

The reason this is a problem is some sites run program that downloads and

installs the product (i.e. I-News and Logitech QuickC am software).

I have stopped all startup programs and all non Microsoft services in

msconfig and uninstalled several programs that I thought might interfere.

I think it might be a registry value but do not know where to look. Any help

would be appreciated.

Sam Roe