Cannot download drivers or revised programs due to 'security settings'

My PC won't allow me to download a new version of Adobe Reader or drivers for my Epson scanner  - a long-standing problem if I move the laptop to another location 'bare' and bring it back and reconnect everything - it's used as a desktop - I always have to re-load the drivers from the Epson CD, even though they are still on the HDD.. Everything else (printer, etc.) works okay. This time, though, even after deleting the Epson program, it shows an error message halfway through the installation and restarts continually. 

The security problem is that when trying to download from Adobe I get a window up which reads 'Your computer security settings will not allow you to carry out this action.' It also did this between deleting an almost expired McAfee security program and before loading a new Norton program and with my AOL firewall off.  I've tried turning Norton off for 15 mins but not sure if I've turned all the relevant parts off. Has my PC fallen out with me? It's all beyond me, I'm afraid.. Thanks for any help.. (Running Vista..)